Heavy-Duty Engine Rebuilding
Practices
4% United States
|M^pUIl Environmental Protection
hI Agency
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Heavy-Duty Engine Rebuilding
Practices
Manufacturers Operations Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
United States
Environmental Protection
tl Agency
EPA-420-R-95-104
March 1995
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PREFACE
Section 202 (a) (3) (D) of the Clean Air Act (CAA), as amended in
1990, requires EPA to study the practice of heavy-duty engine
(HDE) rebuilding and the impact of rebuilding on engine
emissions. On the basis of this study and other relevant
information, EPA may prescribe requirements to control rebuild
practices.
This document, the first of a two part report, summarizes EPA's
findings concerning rebuild practices and discusses, among other
things, specific heavy-duty engine rebuilding practices, types of
rebuilders, frequency and number of rebuilds, and model years of
engine involved in rebuilds.
The emissions impact of rebuilding will not be determined until
later in this study. The objective of this report was to gather
information to develop an emissions test program for rebuilt
engines. Since rebuild emissions data are virtually nonexistent,
EPA will be required to conduct testing and the decisions as to
which types of engines to test will be based on the findings set
out in this report. The actual emissions data generated and the
analysis of the relevance of that data will be included in a
separate report.
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Table of Contents
Chapter 1 - Executive Summary
1.1 Executive Summary 1
Chapter 2 - Introduction
2.1 Clean Air Act Amendments Requirements 3
2.2 Study Schedule 4
Chapter 3 - Data Collection Methods and Sources
3.1 Methods .. 6
3.2 Respondents to Federal Register 7
3.3 Truck Population Data Sources 8
Chapter 4 - Background
4.1 General Heavy-Duty Overview 10
4.2 Engine Classes and Useful Life Definitions 11
4.3 Economics of Rebuilds - Why Rebuild? 13
4.4 Rebuild Definitions .. 15
4.5 Types of Rebuilders 18
Chapter 5 - Diesel Rebuild Practices
5.1 Introduction 20
5.2 Diesel Rebuild Practices 20
5.2.1 Fleet Practices 23
5.2.2 OE Rebuilders 25
5.2.3 Independent Rebuilders 27
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5.3 Diesel Component Replacement 28
5.3.1 .Out-of-Frame Component Replacement 31
5.4 Rebuild Frequency 36
5.4.1 LHDDE Rebuild Frequency 36
5.4.2 MHDDE and HHDDE Rebuild Frequency 38
Chapter 6 — Gasoline Rebuild Practices
6. l Introduction 44
6.2 Rebuild Practices 44
6.3 Component Replacement 46
6.4 Rebuild Frequency 48
Chapter 7 - Rebuild Market
7.1 Truck Populations 50
7.2 Heavy-Duty Truck Mileage Accumulation 52
7.3 Estimated Annual Rebuilds - HHDDE's 53
y
7.4 Estimated Annual Rebuilds - MHDDE's 57
7.5 Estimated Annual Rebuilds - LHDDE's 59
7.6 Model Years of Heavy Diesels Being Rebuilt 61
7.7 Estimated Annual Rebuilds - HDGE's 62
7.8 Model Years of Heavy Gas Engines Being Rebuilt . 63
Chapter 8 -• Emissions from Rebuilt Engines
8.1 Emissions Impacts of Rebuilt Gasoline Engines .. 64
8.2 Emissions Impacts of Rebuilt Diesel Engines .... 65
8.3 EPA Testing 67
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Appendices ^ .
Appendix A - Federal Register Request for Information
Appendix B - Respondents to Federal Register Request
for Information
Appendix C - CARB Component Replacement Tables
Appendix D - Jasper Engines Rebuild Parts List
Appendix E - MOBILE 4.1 Registration Charts
Appendix F - MOBILE 4.1 and EEA Mileage Accumulation
Charts
Appendix G — MOBILE 4.1 Vehicle Miles Traveled Chart
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Chanter 1 - EXECUTIVE SUMMARY
1.1 Executive Summary
The clean Air Act Amendments of 1990 required the
Environmental Protection Agency (EPA) to study heavy-duty engine
rebuilding practices and their impact on engine emissions. On
the basis of this study and other relevant information, EPA may
prescribe requirements to control rebuilding practices.
EPA determined that there are about 350,000 heavy-duty
engines rebuilt each year representing about five percent of the
estimated 7.5 million heavy-duty trucks in operation. Heavy
heavy-duty diesel rebuilds account for about 250,000 of these
rebuilds. Within the heavy heavy-duty diesel population, EPA
estimates that these 250,000 rebuilds represents 16 percent of
the fleet. Medium diesels account for approximately 70,000
rebuilds annually, or nine percent of the medium diesel fleet.
EPA found that light diesels and gas engines are generally not
rebuilt unless an engine failure has occurred early in the life
of the engine.
»
A typical heavy heavy-duty diesel will be rebuilt three
times before retirement. Removable cylinder liners facilitate
the rebuilding process of heavy heavy-duty engines. Medium
heavy-duty diesels are generally not sleeved and subsequently
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will usually undergo only one rebuild. Those light diesel and
gas engines that are rebuilt are generally rebuilt with short or
long blocks1 .
EPA estimates that over 50 percent of all diesel rebuilds
are in-frame rebuilds, which are performed with the engine still
in the vehicle. Most of these rebuilds are performed by owners,
fleets, and shops who use primarily original equipment (OE) or OE
equivalent parts. Retrofitting older engines with new parts
specifically to reduce emissions is burrently not performed
except on a small number of bus engines.
EPA will use the above information to design the emissions
test program that will constitute the second phase of our study.
We expect, based on this information, that the test program will
be limited to large diesel engine testing as the number of
gasoline engine rebuilds is insignificant.
1Short block is an incomplete engine assembly usually consisting of
the cylinder block, crankshaft, pistons and rings, oil pan and
gaskets. Long blocks generally contain the same components as
short blocks with the addition of cylinder heads, camshaft and
timing gears.
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Chanter 2 - INTRQDUCTTDW
2.1 Clean Air Act Amendments Requirements
Section 202 (a) (3) (D) of the 1990 Clean Air Act Amendments
requires the Administrator to study heavy-duty engine rebuilding
practices.
"REBUILDING PRACTICES.- The Administrator shall study the
practice of rebuilding heavy-duty engines and the impact
rebuilding has on engine emissions. On the basis of that
study and other information available to the Administrator,
the Administrator may prescribe requirements to control
rebuilding practices, including standards applicable! to
emissions from any rebuilt heavy-duty engines (whether or
not the engine is past its statutory useful life), which in
the Administrator* s judgment cause, or contribute to, air
pollution which may reasonably be anticipated to endanger
public health or welfare taking costs into account. Any
regulation shall take effect after a period the
Administrator finds necessary to permit the development and
application of the requisite control measures, giving
appropriate consideration to the cost of compliance within
the period and energy and safety factors."2
The Act does not establish statutory deadlines for EPA* s
study and provides the Agency with no guidance in terms of the
rebuilding practices EPA is required to study. Therefore, before
EPA could proceed with the study, it first had to determine
exactly what practices it should study. »
EPA's. current definition of heavy-duty useful life was
2Clean Air Act Amendments of 1990, Sect. 201; amends Sect 202 (a)
(3).
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established in 19833, and was based on the mileage at which
different categories of heavy-duty engines were generally rebuilt
or replaced. For recall purposes, manufacturers of engines would
then be responsible for in-use emissions based on 75 percent of
the useful life. Once past this useful life, the manufacturer
would no longer be subject to in-us6 compliance testing. Some
engines, particularly heavy diesels, operate up to mileages five
times or more their statutory useful life with rebuilds. These
engines could be unregulated emitters for 80 percent of their
lives.
EPA therefore determined that the appropriate focus for this
study was those practices typically performed at or near the end
of the useful life of an engine that are intended to
substantially increase the actual life of that engine. While
these practices do not include engine replacement or minor engine
repair, they do include a variety of practices generally known as
rebuild, remanufacture, and overhaul. These terms are discussed
t ¦
in Chapter 4.
2.2 Study Schedule
0
There are two phases to the required study as shown below:
3See 40 C.F.R. 86.085-2, 48 Fed. Reg. 52170 (Nov. 16, 1983).
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Phase I: Conduct a study of the current heavy-duty rebuild
market, including identifying the key players in the rebuild
industry, the rebuild practices currently, employed by
industry, and the frequency with which rebuilding occurs.
This report is a summary of the findings of Phase I.
Phase II: Using the results of Phase I, conduct emissions
testing of rebuilt engines. The information gathered in
Phase I will help EPA to construct an emissions test program
which will allow EPA to estimate the emission impact of the
rebuilding practices occurring in industry. With these
emissions data, EPA will determine the emissions impact of
rebuilding.
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Chapter 3 - DATA COLLECTION METHODS AND SOURCES
3.1 Methods
The key to meeting the broad charge that Congress gave EPA
in studying the heavy-duty rebuild industry was to gather data on
as many aspects of the industry as practical by involving as many
industry sources as possible. EPA sought to obtain data that
showed both general industry rebuild practices as well as the
number of rebuilds that were being performed on a yearly basis.
Data collection involved many different techniques and we reached
a wide variety of sources.
The primary data collection method utilized was a Request
for Information Concerning Heavv-Dutv Engine Rebuild Study
published in the April 4, 1991 Federal Register.4 The Request
is provided in Appendix A. This method enabled us to reach not
only major trade associations and engine manufacturers, but any
other interested parties as well. Response to the Request was
voluntary, but EPA provided advanced notification to those
industry members who had shown interest in the study or who we ,
believed would want to provide comments. ,
Telephone interviews and follow-ups played an important role
*56 Fed. Reg. 13825 (Apr. 4', 1991).
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in verifying and adding to data obtained through the Request for
Information. Telephone interviews were also utilized in
gathering data from parties that wished to provide input to 'the
study but did not wish to submit any formal written response.
Probably the most important aspect to this technit^ue was that it
provided a means to ask respondents clarifying questions that
arose during the information gathering procedure which were not
addressed in their response to the Request.
Facility visits were also used in our data collection.
There are three main types of rebuilders; fleets, independents,
and engine manufacturers. We visited one facility of each type.
The facilities visited were Jasper Engine and Transmission
Exchange (independent), Mack Trucks, Inc. (Hack) (engine
manufacturer), and Preston Trucking (fleet). These sites were
chosen as typical of each type in terms of their rebuild
practices. In the case of Jasper and Mack, data gathered from
the visits supplemented their formal responses to the Request.
3.2 Respondents to Federal Register .
Twenty seven parties provided written responses to the
Request for Information. These respondents, with a brief
description of their functions, are listed in Appendix B.
Responses ranged from general policy statements to detailed
answers to all fifteen questions.
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IsJ Truck Population Data Sources
Determining the number of rebuilds being performed in the
heavy-duty industry required data that showed the number of
heavy-duty trucks in use and, more importantly, quantifying when
the engine rebuilds are occurring in the engines' lifecycle.
EPA used heavy-duty truck population figures from a variety
of existing sources. These sources include the Bureau of the
Census Truck Inventory and Use Survey (TIUS) for 1977, 1982, and
1987, EPA's M0BILE4.1 Motor Fuel Consumption and Emission Factor
Model. Motor Vehicle Manufacturers Association's Facts and
Figures for 1985-1990, and Energy and Environmental Analysis,
Inc. (EEA's) 1989 Motor Fuel Consumption Model (MFC). MOBILE 4.1
data were used predominantly because it provided the number of
trucks on the road by model year and fuel type. Also, MOBILE is
EPA-generated, based on TIUS data, and has been in use for many
years as a prediction model for emissions by the agency.
EPA relied on two main sources for data describing how often
or under what circumstances engines are rebuilt. First, data
gathered from the Request concerning rebuild practices frequently
addressed the point at which heavy-duty engines were rebuilt,
especially by each particular respondent. Second, we used data
compiled as support for the useful life regulations promulgated
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in 1983s.
5See note 3, Clean Air fcocket No. A-81-11.
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Chapter 4 - BACKGROUND
4.1 General Heaw-Dutv Overview
EPA defines a heavy-duty engine as any engine which the
manufacturer could reasonably expect to be used for motive power
in a heavy-duty vehicle.6 Typical heavy-duty vehicles include
large pick-ups, construction vehicles, dump trucks, straight
trucks, delivery vans, tow trucks, buses, and over-the-road
tractors (semi's). These vehicles usually range in weight from
8,501 lbs. gross vehicle weight (GVW) to as high as 150,000 lbs.
GVW or more and are generally powered by either gasoline or
diesel fuel. Other fuel types such as compressed natural gas
(CNG), liquid petroleum gas (LPG) and methanol are being used
experimentally in some fleets.
Gasoline heavy-duty engines were historically carburetted,
with lighter GVW vehicles using catalyst technology for emission
control. Since the implementation of the 1987 heavy-duty
gasoline emissions standards, many heavy gasoline engines heive
utilized computer controlled fuel injection systems similar to
those found in light duty passenger cars and trucks. In fact,
many heavy-duty gasoline trucks are indistinguishable from their
light duty counterparts except for their load-carrying
640 C.F.R. 86.082-02 (b) ;
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capabilities. Jieavy-duty gasoline engines are generally of the
V-8 block design, but are not designed to be rebuilt. In 1990,
there were no gasoline engines produced with removable cylinder
sleeves to facilitate rebuilding.
Heavy-duty diesel engine and fuel system advances have also
been required to meet ever tighter emission standards. Due to
these tight standards and continuing pressure for increased fuel
economy, changes have been implemented in piston design, fuel
injector design, turbo matching, aftercooling, fuel system
calibration, and now electronic controls are being used.
Many lighter diesels are of the V-8 design, but unlike other
heavy-duty engines, very large diesels are six cylinder in-line
engines. Most large diesel engines have pressed-in cylinder
sleeves designed for easy rebuild. Medium and lighter diesels
are generally not sleeved for rebuilding.
4-i_2 Engine Classes and Useful Life Definitions
There are five categories of heavy-duty engines as defined
by EPA. These categories are meant to reflect the primary
intended service class of an engine.
EPA classifications of heavy-duty engines are given below7:
740 C.F.R. 86.085-2.
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EPA Heaw-Dutv -Engine Category
light heavy-duty gas (LHDG)
heavy heavy-duty gas (HHDG)
light heavy-duty diesel (LHDD)
medium heavy-duty diesel (MHDD)
heavy heavy-duty diesel (HHDD)
Intended GVW Range
8,501-14,000 lbs.
14,001 lbs. and higher
8,501-19,499 lbs.
19,500-33,000 lbs.
33,000 lbs. and higher
Each of these categories has an associated useful life as
follows8:
EPA heaw-dutv Engine Category
light heavy-duty gas
heavy heavy-duty gas
light heavy-duty diesel
medium heavy-duty diesel
heavy heavy-duty diesel
Useful Life
8 years/110,000 miles
8 years/110,000 miles
8 years/110,000 miles
8 years/185,000 miles
8 years/290,000 miles
Many engines, particularly heavy heavy-duty diesels, are on the
road for periods significantly in excess of their statutory
useful lives, in large part because of engine rebuilding. As
described in EPA's 1983 rules and Section 2.2 of this report,
current EPA in-use enforcement programs only target engines up to
75 percent of their useful lives. Therefore, the emissions from
many rebuilt engines are unknown and unregulated. Potential
issues include whether or not rebuilding practices lead to excess
®40 C.F.R. 86.085-2.
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emissions, whether engines are on the road so long that even
small emissions increases due to rebuilding are significant, and
whether changes in rebuilding practices could reduce the quantity
of pollutants being emitted.
Ll2 Economics of Rebuilds - Whv Rebuild?
EPA found that engines are rebuilt for a number of reasons
including increased oil consumption, loss of performance, poor
fuel economy and engine failure. However, the driving force
behind an owner's decision to rebuild instead of choosing other
options is economics. When the engine wears or experiences a
major failure, owners must decide between rebuild, repair,
purchase of a new engine, purchase of a new vehicle, or no
action.
Diesel engines, specifically medium heavy-duty and heavy
heavy-duty, can be rebuilt at a cost significantly less than the
cost of a new engine or vehicle. Since these engines are sleeved
and designed for rebuild, parts are readily available at
competitive prices. An in-frame diesel engine rebuild can be
performed for $5,000 or less, depending on which parts ar?
replaced. (Component replacement will be covered in more detail
in Chapter 5). Out of frame rebuilds, which are generally more
extensive, can be completed for about $3,000 - $12,000, depending
on the engine type. In most cases, rebuilding the engine costs
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substantially less than choosing an alternative to rebuild. For
example, one can expect to pay over $10,000 for a new heavy
heavy-duty diesel engine and as much as $120,000 for a new over-
the-road truck.9
Medium and heavy diesel truck bodies will generally last
much longer than the statutory useful life of the engine, meaning
owners will rebuild an engine several times before replacing the
truck. Not until the engine has significant miles and has been
rebuilt at least once will the owner face the choice of engine
replacement or vehicle trade-in versus further rebuild or repair.
Light diesel and gasoline engines present a less obvious
choice to the owner. Because these engines are not sleeved,
rebuilding requires engine removal from the truck. Removal is
time consuming and costly. Also, unlike larger diesel truck
bodies, light diesel and gasoline truck bodies usually do not
last much more than one to two times the useful life (110,000 -
220,000 miles) of the engine. By the time the engine has enough
mileage to warrant a rebuild, the truck body will likely also
need to be replaced.
0
Most light diesel and gasoline rebuilds are performed as a
result of engine failure. Engines that experience a major
failure at low mileages will likely be repaired or rebuilt
9The Truck Blue Book. Maclean Hunter Market Reports, Inc., ®1989.
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because the owner can still realize significant service life from
the vehicle. . If these same failures occur on a high mileage
truck, the owner may not perform rebuild or repair, but may
instead replace the entire vehicle. Rebuild costs on these
engines range anywhere from about $1,000 for a short block up to
$5,000 for' a complete engine.
LlA Rebuild Definitions
"Rebuild", "remanufacture", "overhaul" and "repair" are
often used interchangeably and could all be considered "rebuild
practices". Thfe following summarize comments EPA received from
various industry sources, and reflect the range of terminology
used by the heavy-duty industry. EPA did not receive any
comments which specifically defined the component replacements or
combinations of component replacements that constitute a rebuild.
Rebuild: This operation generally involves the disassembly
of the engine to a point where high wear components can be
checked and measured against specifications, replaced or
reconditioned as necessary, and reassembled. Often, certain
components are replaced regardless of condition including
engine bearings, piston rings and gaskets. This can be done
with the engine still in the chassis. Some feel that a
rebuild must be performed with the engine removed from the
chassis so that certain components and measurements can be
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checked tha»t cannot be inspected in-frame.
Overhaul: To some, this operation is indistinguishable from
a rebuild as defined above, although an overhaul is almost
exclusively done in-chassis. On the other hand, many
consider an overhaul to be an engine disassembly to remedy a
specific engine failure in which only the failed part or
parts are reconditioned and/or replaced.
Remanufacture: Most agreed that remanufacture is a
production-type process in which a core engine (owner trade-
in) is completely disassembled and every part is checked
against original equipment (O.E.) specifications for
reusability. Parts that meet specifications are then
inventoried and stocked in supply; parts that are not in
specification are machined, if possible, or discarded.
Engine reassembly is based on market demand and is performed
using a combination of new and old parts. Customers usually
purchase an engine of the same configuration engine they
traded in, and the "new" product is generally dynamometer
tested and warranted.
In a different context, EPA proposed the following definition of
an engine rebuild for urban buses10:
1056 Fed. Reg. 48350 (Sept. 24, 1991).
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"Engine Rebuild" means an activity, occurring over one or
more maintenance events, involving disassembly of the engine
including the removal of the cylinder head(s) and the
replacement or reconditioning of more than one major
cylinder component in more than half of the cylinders."
»
where
"Major Cylinder Component" means piston, cylinder liner,
connecting rod, or piston ring set."
Along with the definitions above, there are two other terms
often used in the industry which can be considered a subset of
rebuilding. These are:
Uprating: This process involves rebuilding, overhauling or
remanufacturing an engine with parts such that the power
output of the rebuilt engine is greater than that of the
' V.; i .
original engine. Engines are generally uprated to a
certified configuration with a higher horsepower or torque
rating.
Retrofitting: this involves rebuilding an engine with parts
designed to increase the emissions performance (decrease
emissions) from those of the original engine configuration.
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.— . ¦ - - . -in. «n ¦ ¦ .-r^raa
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4.5 Types of Rebuilders
Rebuilds are performed by three basic groups within the
industry; Original Equipment Manufacturers (OEM's), independents
and fleets. OEM's are exclusively production style
remanufacturers who sell complete and partial engine assemblies,
fuel systems, and other parts. In 1990 there were approximately
twenty OEM's involved in the production of new assembly line
engines. Although all twenty undoubtedly supply replacement
parts which are used by rebuild shops and fleets to service and
rebuild engines, EPA is aware of only six who perform or contract
out assembly line type remanufacturing of engines. Fleets
«
perform rebuilds and overhauls in and out-of-chassis on an as
needed basis and may rebuild engines for other fleets. Thousands
of fleet are currently operating in the U.S. so it is impossible
for EPA to estimate the number which may actually be involved in
engine rebuilding. EPA expects that most large fleet operations
*
are involved in some form of engine rebuilding. Independent
rebuilders can be either production type operations or small
repair type facilities. Some larger independent rebuilders are
under contract with OE manufacturers to rebuild for them., A
subset of the independent rebuilder category includes franchised
truck dealerships which are independently owned and operated
under a franchise agreement with OE manufacturers. There are
approximately 2,700 truck dealer outlets.
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Major trade associations exist which represent each group of
•« •
rebuilders. The Engine Manufacturers Association (EMA)
represents OE manufacturers, the Automotive Engine Rebuilders
Association (AERA) represents independent rebuilders and the
American Trucking Associations (ATA) represents fleets.
Membership is often held in more than one association.
In addition to the three major types of engine rebuilders,
there are numerous individual engine component rebuilders and
aftermarket parts producers. The products generated by these
rebuilders and suppliers are used extensively in the engine
rebuild industry and are discussed in this report.
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Chapter 5 - DI-ESEL REBUILD PRACTICES
5.1 Introduction
There is a marked difference between diesel and gasoline
engine rebuild practices. While diesel engines in general make-
up only forty percent of the heavy-duty engine population, heavy
heiavy-duty diesel engines (class 6-8) outnumber heavy heavy-duty
gasoline engines three to one. Gasoline engines are used in more
short route applications while diesels are used in long haul
jobs. The different usages often translate into different
rebuild practices.
5.2 Diesel Rebuild Practices
Diesel rebuild practices can be divided into two main
categories; in-frame and out-of-frame rebuilds. In-frame rebuild
practices are not as extensive as out-of-frame practices. In-
frame s generally do not include any machining of the block or
crankshaft, but do include, among other items, replacement of the
major stress-bearing engine parts such as pistons and bearings.
Out-of-frames include all the above as well as the aforementioned
machining.
In a normal sequence of engine rebuilding,.an engine will
have an in-frame rebuild before it undergoes the more-involved
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out-of-frame rebuild. This in-out series will continue until the
engine is scrapped or suffers a major failure that requires it to
be removed from the chassis prematurely and receive out-of frame
service.
Engine owners look to several parameters when determining
when to rebuild the engine, all of which have underlying economic
reasons. The main signaling parameter used is oil consumption or
oil analysis.11 The need for rebuild is indicated when an
engine is burning too much oil or when an oil analysis shows
excessive contaminants or metal shavings in the oil. Engine
manufacturers have oil analysis guidelines that signal the need
for a rebuild.12 Increased oil consumption is a signal that the
piston rings are worn, the piston sleeve diameter has increased
beyond its tolerance, or that bearings are out of specification.
The next category is loss of performance and/or decreased
'•'A
fuel economy. These criteria typify increased engine wear.
However, decreased fuel economy does not necessarily mean that
engine internal components have worn beyond their tolerances.
Reduction in fuel economy could also be attributed to a worn or
maladjusted fuel injection pump. Therefore, decreased fufl
11 Survey Data Research, A study to Determine Engine Rebuild Criteria
Among Owners of Diesel Powered Vehicles. 1981. This study was
performed for EMA.
12Operation and Maintenance Manual. 3406B Truck Engine. Caterpillar,
1990.
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economy is usually accompanied by one of the internal engine wear
signals before a determination will be made to rebuild the
engine.
Failure of a major internal engine component may also lead
to rebuild if the engine is approaching rebuild mileage. The
owner may rebuild the engine while replacing the broken part
since the truck will be out of service for the least amount of
time.
Engine miles, hours, or years in service are not generally
used to schedule rebuilds. Fewer than one third of all fleets
that commented stated that they used miles driven as a rebuild
criteria,13 and a similar fraction of the American Truck Dealers
Division of the National Automobile Dealers Association
(ATD/NADA) respondents mentioned these as criteria used in
determining when to rebuild a HDDE.U Sound rationale exists as
to why these factors are not used. Diesel engines are involved
in a wide variety of applications and accumulate mileage and
hours at varying rates. It would not be economical to schedule
rebuilding at a set mileage or hour level because the engine
might not need a rebuild at that point. Owners do sometimes look
at mileage or hours as a criterion to determine engine condition;
13See note 11.
UATD/NADA response, dated June 6, 1991, to EPA's Request for
Information.
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high miles, hours, or years may alert the owner to look for other
signs of engine wear that signal the time for a rebuild.
5.2.1 Fleet Practices
Fleet heavy-duty engine rebuilding varies and is mainly
dependent on the size of the fleet. Large fleets, such as
Preston or Roadway, have centralized, mostly self-sufficient,
maintenance facilities that do their own rebuild work. These
facilities have full-time mechanics, machining equipment, and
other support required to perform rebuilds and in many cases are
authorized by OE's to work on their engines. These fleets also
have local maintenance shops, but these shops do mainly
preventive maintenance and emergency repairs in support of the
local fleet. When it is determined that an engine needs a
rebuild, the fleet either removes the engine from the truck and
ships it to its rebuild facility or sends the truck there. If.
the rebuild requires that the engine be removed, an engine wit^i
the same configuration, which was previously rebuilt, is
installed in the truck so that it is not out of service for an
extended length of time. The removed engine will then be rebuilt
and put into storage until it too is needed as a replacement
engine.
At a typical fleet rebuilding facility, engines either
receive an in- or out-of-frame rebuild. A parts depot on site
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provides mechanics with the proper replacement parts. In some
« •
cases, such as starters, the facility will rebuild worn parts.
Fleets will generally replace with a new part or subcontract out
to a specialty shop complex parts such as the fuel injection
pumps and turbochargers because it is cheaper than maintaining
the specialized personnel and equipment necessary to rebuild
these items. Out-of-frame rebuilds are usually dynamometer
tested to ensure that operating characteristics such as
horsepower and fuel flow are in specification before the engine
leaves the shop.
Smaller fleets generally will not have the resources
necessary to perform out-of-frame rebuilds, so when an out-of-
frame is required, these fleets will use either an independent or
OEM assembly-line rebuilder or a local rebuild shop. In-frame
rebuilds can be performed by these smaller fleets, but they may
also have this service performed at a dealership or independent
shop.
~
Engine emission and part number labels are generally not
removed from fleet-rebuilt engines since the same core is used.
However, new labels stating that the engine was rebuilt aye not
affixed to the engine.. Instead, owner records or rebuild shop
invoices must be referenced in order to determine if it has been
rebuilt.15
15ATA response, dated May 8, 1991, to EPA's Request for Information.
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5.2.2 OE Rebuilders
Several OE's have their own assembly-line rebuild
facilities. When a core engine is traded-in, it is stripped down
and cleaned. At this point the engine loses its "identity"
because all labels are removed and very often the serial number
is ground off the block. Major components are inspected and
checked to see if they are in specification or can be put into
specification - otherwise they are scrapped. For example, one
manufacturer scraps 50 percent of the crankshafts it receives.
Fuel injection pumps and turbochargers are disassembled and
rebuilt with new parts. Sometimes these components are returned
to their original manufacturer in an exchange program with the
rebuilder. Other components such as pistons, bearings, and
valves are almost always scrapped.
Once disassembled and cleaned, the engine is ready to be
reassembled. Unless the block is a unique and seldom used
design, it is usable in different engine configurations. Very
often, just changing the fuel delivery specifications will change
the calibration of the engine. Once it is decided what
configuration to build, the engine proceeds down the assembly
line with a document attached to it that tells the assembler or
machiner which specifications or parts are necessary for that
engine configuration. As a means of documenting proper
replacement of parts, mechanics are generally required to initial
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P-32
the engine build form.
When the engine has been completely rebuilt, a new metal
label showing the engine rebuild date along with various engine
settings is riveted to the block. This label replaces the
original engine specification label that was removed in the
cleaning process. The type of label and the information on it
varies among manufacturers. The engine would also get a new
serial number ground into the block at this time, if needed. The
final step before shipping the rebuild is to test it on the
dynamometer. No specific tests for emissions are done. These
engines are warranted by the remanufacturer.16 This entire
process is generally known as remanufacturing.
In-frame OE rebuilding facilities do not exist as stand-
alone shops. They are usually associated with dealerships and/or
distributorships. These shops operate just like any car
dealership, with the truck owner bringing his truck to the shop
and having work performed on his truck on the premises. Rebuilt
16Warranties on remanufactured engines generally run for one year
with unlimited mileage, though some plans set the mileage limit at
100,000 miles. Some OE warranties require that OE parts be used.
Examples of these programs are the Cummins National Overhaul
Warranty (NOW) and Caterpillar Overhaul Protection for Trucks (OPT)
plans. These two plans cover both in-frame and out-of-frame
rebuilds and let the owne? receive service on his engine at any
factory authorized repair facility. Customers can also purchase
extended warranty protection plans. However, warranties are seldom
actually needed. According to AERA, only 2 percent of all rebuilt
engines are returned for in-warranty service, with 40 percent of
these repairs attributed to the customer installing the engine
incorrectly or misdiagnosing the initial failure.
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P-33
engines from these facilities are generally not labeled-, nor are
the original lSbels removed. Therefore, it is difficult to
identify an in-frame rebuilt engine without invoices or other
records. Also, if a fleet is authorized to perform service work
on an engine by the manufacturer, then all servicing would be
done at the fleet maintenance facility.17
5.2.3 Independent Rebuilders
Independent rebuild facilities exist in a variety of forms,
from large assembly-line shops to small specialty shops that only
rebuild one specific part of the engine, such as the cylinder
head or turbocharger. Assembly-line facilities operate in a
similar manner to OE assembly-line facilities. An engine owner
goes to an distributorship where he exchanges his old engine for
a rebuilt model that is in stock. In the event that the
customer's engine is not a commonly-rebuilt engine, the owner's
engine is removed, shipped to the plant, rebuilt, and returned.
In this case, the owner receives the same block that he turned
*rc •
in. Otherwise, core engines are gathered from the
distributorships and are shipped to a central rebuild facility.
The engines are stripped, cleaned, and rebuilt to the required
configuration. Again, the block is not necessarily used for the
exact same engine if it is compatible with otheir configurations.
17Labor may be warranted by the dealer who performed the rebuild
while parts are warranted by the manufacturer.
Page 27
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Specialty shops often rebuild certain components or systems
in support of larger rebuilders. They also provide rebuilt parts
to owner-operators who choose to do their own engine work.
Diesel Component Replacement
Parts replacement is the defining factor of a rebuild. By
looking at what parts were replaced, one can usually tell the
degree of rebuilding an engine has undergone, either in-frame or
out-of-frame. However, a core group of components are replaced
during all rebuilds. Frequently, only these parts, the main
stress bearing and lubricating components, will be replaced
during an in-frame rebuild. The EMA study listed piston rings,
pistons, connecting rod bearings, main bearings, cylinder liners,
injector and nozzles, and cylinder head assembly as parts that
fleets replaced over 85 percent of the time during a rebuild.18
The reported numbers were similar for owner/operators, although
owners included other ancillary parts such as air compressors and
turbochargers. This difference could be that owner/operators
generally have less structured preventative maintenance plans
than fleets and therefore find the need to replace more engine
items at rebuild. •
Data gathered in our study supported the EMA figures.
Overnite Transportation, a large fleet, stated that pistons,
18See note 11.
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rings, liners,,bearings, and heads are replaced during their in-
frame service.19 The majority of survey respondents reported
that six out of the seven parts are almost always replaced when
they are rebuilding an engine.20 There was a roughly even split
between "always replace" and "replace when necessary" when it
came to injectors and nozzles. The respondents who did not
automatically replace this part said they performed functional
testing and replaced if needed. Remember.that ATD/NADA members
are generally OE-authorized maintenance facilities and are
performing virtually all of the in-frame work for the OE's.
Appendix C shows reported in-frame and out-of-frame component
servicing practices for fleets and rebuild shops as determined by
a study of heavy-duty diesel rebuilding practices done for CARB
in 1987.21 These figures support EPA findings.
While the seven core parts are almost always replaced during
an in-frame rebuild, this is not the only service work done on
the engine at. the time. Other systems and parts, such, as
turbochargers, camshafts, and connecting rods, are inspected and
repaired or replaced if needed. In some instances, even these
parts are rebuilt or replaced automatically. But generally,
0
19Phone conversation with representative of Overnite Transportation,
May 29, 1991.
20See note 14.
21 "Survey of Heavy-Duty Diesel Engine Rebuilding, Reconditioning,
and Remanufacturing Practices", sierra Research, Inc, August, 1987.
Prepared for California Air Resources Board (CARB), CARB contract
#A4-152-32.
%
Page 29
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unless the owner has complained about a specific problem that can
* •
be traced to a part or the rebuilder notices excessive wear or
maladjustment, these parts are not changed during an in-frame
rebuild.
Almost all engines are rebuilt to a certified configuration
regardless of the type of parts used. Some ATD/NADA respondents
stated that a small percent of their customers want their engines
uprated for more power. Uprating does have a practical limit,
though. Core credit practices serve to narrow the uprating that
is economically reasonable to adjustments made to equipment
already on the engine. Requiring wholesale changes or using new
parts would increase the rebuild cost. The resulting uprated
configuration, therefore, generally uses the same parts as the
original. However, the fuel system may be calibrated
*
differently. Note that these uprated configurations are most
always a previously certified configuration and new
configurations are generally not created. In theory, uprating
should have only a marginal emissions impact because engines are
generally only changed from one engine configuration to a
different, more powerful configuration within the same engine
family. The emissions certification data for a heavy-duty engine
family reflect the worst-case emissions configuration within that
family. Therefore, in theory, the uprated configuration would at
worst reflect the configuration used to determine certification
emissions data.
Page 30
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5.3.1 Out-of-Frame Component Replacement
¦m •
Out-of-frame rebuilding lends itself to more extensive
component changes. Since the engine is disassembled, all
components are checked iand, if necessary, replaced. All
rebuilders, including in-frame rebuilders, have a parts exchange
credit policy that allows them to work with their customers in
processing engines. Owners receive a monetary credit for various
parts of old engines such as the crankshaft, block, and fuel
injection pump. This core credit program exists because for many
engine items, it would reduce profit or increase the price of a
rebuild if the rebuilder had to replace all worn parts with new
ones. The credit price is set so as to encourage the customer to
include these parts with the engine. For example, Cummins
charges 50 percent of the price of a new injection pump for a
remanufactured unit when the old unit is exchanged, but this
figure jumps to 70-75 percent of the new price without an
exchange. Volvo charges $1,120 for a remanufactured crankshaft
with exchange of one which may be remanufactured while a
remanufactured crankshaft without exchange sells for $1,620.22
A core exchange program is critical to the business,
operation of rebuilders because they need the old cores to
actually rebuild. The rebuilder must take in more cores than he
will rebuild due to the fact* that not every incoming core will be
22Commercial Carrier Journal. November, 1990.
Page 31
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P-38
salvageable. The exchange program will also act as a signal to
the owner when a rebuild no longer makes financial sense. The
reduction in credit due to unsalvageable parts will make the cost
of a rebuilt and new engine comparable.
These credit programs vary in scope and range from Mack's
program where they have credit prices for almost every engine
part23 to one of Jasper's policies where the customer receives
full credit if the Jasper representative determines that the core
has not been previously disassembled, there are no visible holes
or cracks in the engine, and the crankshaft turns at least 360
degrees in the direction of engine rotation.24
Due to the nature of assembly-line rebuilding, all engine
parts are replaced with either new, remanufactured, or iri-
specification used parts. When the parts are removed from the
engine, they are checked and either scrapped, rebuilt, or put
into a central bin to be used in other engines. Generally this
practice can be broken down into a general rule of thumb. Low-
cost parts will be replaced while more expensive parts and
systems, such as crankshafts and fuel pumps, will be rebuilt.
This is illustrated by the list of replacement parts and 0
components used by Jasper and is shown in Appendix D.
aData submitted to EPA during a May 8, ,1991, visit to Mack
Remanufacturing Center.
24Jasper sales literature, 1991.
Page 32
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P.39
New replacement parts can either be OE, aftermarket, or
rebuilt parts." 'The type of part used in a rebuild is largely
determined by the type of rebuilder. An OE assembly-line
rebuilder is most likely to use strictly OE parts while his
independent counterpart will probably use a mixture of OE and
aftermarket parts. The majority of ATD/NADA respondents stated
that they use OE parts. The Army uses aftermarket parts
exclusively in their overhauls.25
The choice of what kind of part to use depends on price and
quality. Rebuilt OE or aftermarket parts can provide up to a 40
percent cost savings over a new part26, though the majority of
rebuilt parts will use OE cores. Some rebuilders will use only
OE parts, even if the aftermarket part is exactly the same and
the OE part is twice as expensive. Others feel the same way
about aftermarket parts. Parts availability is also a driving
factor.
The majority of parts initially brought to market result
from OE-sponsored development or coordination with their vendors.
The aftermarket parts, usually with a small modification, are
then introduced into the market. The market share between OE and
aftermarket parts is uncertain, but OE or OE-design parts
2SDepartment of the Army response, dated May 22, 1991, to EPA's
Request for Information.
26APRA response, dated May 13, 1991, to EPA's Request for
Information.
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probably constitute a majority. For example, Detroit Diesel
Corporation (DDC) estimates that its own parts command 60-70
percent of its replacement parts market27, and an 0E fuel
injection system supplier states that its market share for
replacement parts is roughly 75 percent;
The comments received by EPA indicate that many OE and
aftermarket parts are often very similar. In some cases, the
part manufacturer makes both types and the only difference is the
»
packaging. Federal Mogul stated that their engine bearings,
pistons, and carburetors are the same for both OE and aftermarket
use.28 similar comments were received from The Tucker Co., Inc.
regarding valve seats.29 Enginetech, Inc. went even further.
They believe that in many instances the aftermarket part is
better than the OE part because the aftermarket part is designed
to alleviate some problem that developed with the OE engine.30
This is not meant to imply that OE's do not upgrade their parts
in a similar fashion. An example of a product, improvement could
be a different chamfer on a piston ring while a design shortfall
upgrade could be a material replacement for a piston ring that
27DDC response, dated May 20, 1991, to EPA's Request for
Information. ,
28Federal Mogul response, dated May 8, 1991, to EPA's Request for
Information.
^The Tucker Co., Inc. response, dated May 17, 1991, to EPA's
Request for Information.
30Enginetech, Inc. response, dated May 28, 1991, to EPA's Request
for Information.
Page 34
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wears too quickly. The impetus for any upgrade will also depend
«' *
on the demand for the part. In addition, not all aftermarket
parts are of identical quality.
Statistical process control (SPC) is being used by OE and
aftermarket parts manufacturers. This process employs
statistical sampling of the product to verify that manufacturing
tolerances and design specifications set by each parts
manufacturer are being achieved. SPC has become used in the
parts industry as a means to improve quality and provide
assurances to the customer about the quality of the parts. The
parts consumer, either an OE or independent rebuilder, will ask
that SPC be applied to all facets of the vendor's process, not
just the part the customer is buying. Total system satisfaction
is required, meaning SPC can not be applied selectively.
Companies using SPC have reported less than one percent of their
parts are returned under warranty, and that a percentage of these
returns are due to incorrect installation and not manufacturing
errors on the part. Some rebuilders also employ another step in
assuring themselves that the parts they are installing will fit
their application. The rebuilders check the dimensions of the
parts to ensure a correct match.31 The motivation is to ^
alleviate engine returns, which are costly to the rebuilder.
AERA promotes this as sound business practice to its members.
31 Jasper sales literature.
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P-42
Comments received indicate that consolidated, or "will-fit",
•
parts are not prevalent ih the heavy-duty parts replacement
industry. Generally, parts are application specific, meaning
that a part is used on only one engine type of a specific
manufacturer. Replacement parts are designed to meet the
requirements for specific engines. At the same time, there are
parts that can be used on several applications within a product
line. Producing parts in this manner reduces proliferation, but
is generally limited to items such as piston rings, injector
nozzles, and gaskets. This process is incorporated by OE and
aftermarket vendors.
5.4 Rebuild Frequency
There is no consensus in the industry regarding the number
of rebuilds a typical diesel engine receives before the end of
its lifecycle. This is partly a result of the varied diesel
applications. For example, the 1981 EMA study32 states that
"[T]rucks used specifically for long haul driving run their
diesel engines about 37 percent longer before reaching the first
overhaul than trucks used for other purposes.n
5.4.1 LHDDE Rebuild Frequency
A light heavy-duty diesel engine would typically be
32See note 11.
Page 36
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installed in a-cilass 2-5 truck, which would likely be used in
local service as a short delivery or service vehicle. Mileage
accumulation on this truck will be relatively slow, will involve
many short trips, and it will take approximately eight years to
reach the engine's useful life limit. The gradual aging of the
truck and engine means the truck body would normally deteriorate
at a point that is not significantly greater than the engine's
useful life.
Ford, GM, and Navistar engines make up the overwhelming
majority of the light heavy-duty diesel market. Both Ford and gm
have stated that there is no real demand for light diesel
rebuilds. GM has no rebuild facility for diesels, and has not
authorized any facility to perform this service.33 Ford has
authorized a limited number of independent businesses to be Ford
Authorized Remanufacturers34, but it is unclear how many of
these facilities rebuild diesel engines. Rebuild' work on each
manufacturer's engines does occur at their respective
dealerships.
Most OE manufacturers commented that very little rebuilding
••
that extends the useful, life of the engine occurs on light heavy-
duty diesels. Instead, rebuilt sections of the engine,
33Phone conversation with GM representative on April 15, 1991.
^Ford Motor Co. response, dated May 23; 1991, to EPA's Request for
Information.
Page 37
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specifically short and long blocks, are used, and this only
occurs when there has been a major engine failure. Therefore,
EPA believes that light heavy-duty diesel engines undergo at most
one out-of-frame rebuild, probably around 150,000 miles.
However, the vast majority of these engines are never rebuilt, as
will be discussed in Section 7.5.
9t4»2 MHDDE and HHDDE Rebuild Frequency
«
The vast majority of diesel engine rebuilding occurs with
the class 6-8 engines. These engines typically experience long
operation times and high mileage, providing a strong economic
incentive to have an efficient engine. Caterpillar estimates
that approximately 80-85 percent of the operation and maintenance
costs associated with a 1990 3406B engine can be attributed to
fuel costs.33 As discussed in Chapter 4, truck body and chassis
useful life is not the limiting factor that it is with light
heavy-duty diesel trucks. Medium and heavy-duty engines are used
much more frequently (seven times as often) in long-distance
operating models than are light-heavy engines.36 This figure
includes both gasoline and diesel engines. The actual split is
higher because gasoline engines make up the majority of lighter-
class vehicles while diesels predominate in the heavy-duty class.
35See note 12.
^Truck Inventory and Use Survey. 1987. p. US-34.
Page 38
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P.45
The length of time before an engine is retired from use may
vary within the medium and heavy diesel classes due to operator
and usage differences. The EMA study states that class 8 trucks
operate seven percent longer before first rebuild than do class
6-7 engines. It also states that diesel engines in fleets of 50
trucks or more run more than nine percent longer than do similar
engines in smaller fleets. EPA has no data shoving these
figures have changed substantially within the past ten years.
However, these variations fall within the range of miles between
rebuilds, and therefore are not significant.
Industry surveys done in support of EPA's heavy-duty useful
life regulations provide a good start point for determining
frequency of rebuilds for MHDDE's and HHDDE's. The EMA study
reported that 74 percent of all fleets and 81 percent of all
owner operators performed their first rebuild, in-frame and these
figures hold true today.
Ten years ago there was a definite distinction in mileage
between rebuilds of medium and heavy-duty heavy diesel engines,
especially in cases where the medium-duty engine was not ^sleeved.
Only 57 percent of non-sleeved engine owners stated, then that
they rebuilt their engines, and that this service occurred at an
average of 175,000 miles.37 This does not mean that 57 percent
of MHDDE's are rebuilt, because this figure reflected individual
37Fleet Maintenance and Specifying, Vol. 7, No. 5, May 1981, p. 41.
Page 39
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fleet response®•and is not adjusted to account for the number of
engines in each fleet. However, it did reflect the relative
frequency of MHDDE rebuilding. The EMA report stated the average
rebuild mileages for class 6 and 7 diesels was 203,000 and
280,000 miles respectively.3* However, this report did not make
any distinction between sleeved and non-sleeved engines, which
could account for the difference in values. It is also not
unusual to find a HHDDE in a class 7 truck because the owner
might desire more power and also because there can be spme
overlap between the classes. This could account for the reported
difference in miles before rebuild.
The owner of a non-sleeved MHDDE faces a more difficult
decision when determining whether to -rebuild his engine than does
a sleeved engine owner since rebuilding a non-sleeved engine
requires that it be out-of-frame. Owners will be more hesitant,
due to economic concerns, to remove the engine from the truck,
especially if the engine is used in low-mileage service. Without
sleeves, the cylinder must be bored out and a new sleeve or
oversized piston must be installed into the engine. Boring a
cylinder can only be done a few times because removing too much
metal from the cylinder can weaken it and cause the cylinder to
crack. MHDDE's that are sleeved can easily be rebuilt in-frame
more than once, just like HHDDE's. However, sleeved medium
diesel engines do not make up a large part of the market. Only
38See note 11. .
Page 40
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P-47
25-30 percent of the 1990 MY production was sleeved. EPA
estimates that of the remaining 70 percent of the market, roughly
50 percent of these engines will be rebuilt. This figure is
supported by the Fleet Maintenance & Specifying survey stating
that only 57 percent of non-sleeved engine owners rebuild their
engines when faced with the option of rebuild or replace.
In any event, CPA expects that a MHDDE will be rebuilt at
most twice in its lifetime, with a significant percentage not
rebuilt at all. The extended mileage accumulation period and
design features that complicate engine rebuild are the basis for
this determination. The mileage at which MHDDE's are rebuilt is
approximately 200,000-250,000 miles. This figure is based on our
determination that non-rebuilt engines are driven for roughly
200,000 miles before trade-in39 and eventual rebuild. The
majority of one manufacturer's MHDDE rebuilds in 1990 were
performed on engines of the 1981/82 MY.
The rebuild picture is much clearer with heavy-heavy
diesels. Since these engines are designed to be rebuilt, they
make up the bulk of all rebuilds. EPA believes that HHDDE's are
rebuilt on average every 300,000-400,000 miles. This is about
every four years, however the interval varies because as the
engine gets older, it accumulates mileage at a slower rate. The
39Memo from Robert Johnson, SDSB, to Docket # A-81-11, "Derivation
of Heavy-Duty Diesel Engine Average Usage Period", July 1, 1983.
Page 41
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miles-between-retouild interval should remain fairly constant over
the life of the engine.
These figures apply for both in-frame and out-of-frame
rebuilds and are based on a variety of data obtained in the
course of the study. In contrast, EPA primarily looked at miles
until the first major overhaul in the useful life rulemaking.
First, the EMA report gives an average mileage until rebuild of
280,000 miles for class 8 engines while the Fleet Maintenance &
Specifying article gives an average of 281,000 miles for sleeved
engines, which were predominantly class 8's in 1981. over half
the respondents in the ATD/NADA survey stated that mileage
between rebuilds was three to four years and 300,000 ~ 400,000
miles/0 It should be noted that over 72 percent of these
rebuilds are in-frame rebuilds. One OE manufacturer stated that
an out-of-frame remanufactured engine runs between 300,000 -
500,000 miles before it needs another rebuild while another
recommends to its owners that the engine be rebuilt at 500,000 —
600,000 miles. Jasper stated that large engines are rebuilt
around 300,000 - 400,000 miles and follow the in-frame, out-of-
frame sequence. Jasper also said that theoretically, a rebuilt
0-
engine should last as long as a new engine does/1 Many other
respondents throughout the industry made similar statements.
40See note 14.
41Statement from Jasper representative on April 3, 1991, during
facility visit in Jasper, IN.
Page 42
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The typical HHDDE will follow the in-frame, out-of-frame
« *
sequence over its lifetime. It will probably only receive a
total of three rebuilds, meaning, it will get two in-frames and
one out-of-frame. This figure is based on the fact that trucks
simply will not last long enough in order to get four rebuilds.
Trucks that accumulate mileage quickly, such as coast-to-coast
line haulers, will be the exception. However, offsetting these
trucks will be the engines that are involved in fleet trade-in
programs with the OE's. Some of the engines will be traded in,
for a new or rebuilt engine, before the engine gets even a second
rebuild. Yellow Freight trades their over-the-road engines in to
Cummins after five years and generally only one rebuild.42
Another factor indicating that HHDDE's will only be rebuilt three
times is that Jasper and Mack both stated that they very rarely
see any of their rebuilt engines return for a second out-of-
frame.
42Phone conversation on May 28, 1991, with representative of Yellow
Freight.
Page 43
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P-50
Chapter 6 - GASO'LTNt; REBUILD PRACTTflffg
6.1 Introduction
Heavy-duty gasoline engine rebuilding is performed for
different reasons than heavy-duty diesel rebuilding. Neither
LHDGE's nor HHDGE's are rebuilt to increase operational life.
Instead, gasoline engines rebuilds generally occur when the
engine has experienced a catastrophic failure and, in these
instances, generally a short or long block rebuild replacement is
used to alleviate the problem. Very few complete engine rebuilds
occur in the HDGE industry.
There are only three HDGE manufacturers; Ford, GM, and
Chrysler. Chrysler produces a small number of engines per year
compared to the other two and did not provide any comments. For
this study our analysis will be based on comments provided by
Ford and GM.
EPA will treat LHDGE's and HHDGE's as one in this study
because there is no major difference, from a rebuild standpoint,
between these two classes. Any reference to HDGE, therefore
includes both LHDG and HHDG engines.
6.2 Rebuild Practices
Page 44
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P.51
There are'iftajor differences between HDGE and HDDE
rebuilding. For example, there are no OE assembly-line type
rebuild shops for HDGE's. Instead, Ford and GM both authorize
outside facilities to perform rebuild work on their behalf.
These outside facilities include both dealerships and independent
businesses to which the manufacturer provides rebuild
specifications. Ford uses a small number of businesses while GM
has just begun a rebuild program and is currently using only one
outside supplier. These independent rebuilders sell rebuilt
engines to dealerships, for eventual use by the final purchaser.
The OE's act as distributors and the engines are listed with part
numbers like any other stock item.
Fleet rebuilding of gasoline engines is not nearly as
prevalent as with heavy diesel engines. Large line haul fleets
generally do not use gasoline engines, and those that do use them
for pick-up and delivery routes. Certain types of fleets use a
large number of gasoline engines including truck rental companies
such as Ryder, and delivery services such as UPS. The majority
of fleets contacted indicated that they run their gasoline
engines until there is a failure or performance has decreased .
such that a tune-up or parts replacement will not significantly
improve engine performance. If this occurs at a point when the
vehicle is still in good condition, the engine is replaced with a
remanufactured short or long block while the bolt-on emissions
control components are reused. Otherwise, a new truck is
Page 45
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purchased.
HDGE rebuilding is infrequent, when performed, rebuild
practices for HDGE's are essentially the same as those in the
HDDE segment of the industry, with a few notable differences.
First, since no HDGE's are sleeved, in-frame rebuilding is non-
existent. Engine worlc done in-frame on a HDGE will take the form
of a repair, such as cylinder head or fuel system repair, and not
a rebuild. The majority of respondents to the ATD/NADA survey
who performed HDGE rebuilds replied that these rebuilds were
performed out-of-frame. Secondly, since relatively few complete
HDGE rebuilds are done, dynamometer testing is not performed on
the vast majority of remanufactured gas engines. Data received
from Ford and GM highlights the lack of complete engine rebuilds.
6.3 Component Replacement
Parts and components are treated basically the same way in
HDGE rebuilds as they are in HDDE rebuilds. The main stress
bearing and lubrication parts, including pistons, rings, and
bearings, are replaced when the HDGE undergoes an out-of-frame
rebuild. But there are some notable differences. Since the vast
majority of rebuilding is with short and long block rebuilds, the
fuel system (either carburetor or injection) is not included in
rebuilding. This is especially true in assembly-line rebuilding
Page 46
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where the engine owner would remove his fuel delivery system
before rebuild and then reinstall it onto the newly rebuilt
partial engine assembly. The only time the fuel system is
checked is when the engine is rebuilt at a dealership or fleet
facility. In these cases, the fuel system is inspected and
replaced with an OE or rebuilt OE part only if a problem is found
or the owner complained of a performance problem traceable to the
fuel system. Very few of the ATD/NADA respondents stated that
they automatically rebuild or replace a carburetor when
rebuilding an engine. Uprating a HDGE during rebuild is
virtually non-existent because it would involve changing parts,
which would be expensive and difficult, since there are no easily
adjustable parts involved in a HDGE rebuild.
Gasoline engine, rebuilds do not include catalytic
converters. Assembly-line rebullders, both OE and independent, do
not rebuild converters because they do not receive these items
from the owners. An owner who has had his engine rebuilt,
whether it be a short block or complete engine rebuild, will
simply bolt the rebuild back into the truck without changing the
converter. A few of the ATD/NADA respondents said they checked
»»
catalysts when they were performing a rebuild. No direct
operational test exists for catalytic converters but an idle
carbon monoxide test may point: to possible catalyst
deterioration. Therefore, the emissions impact of HDGE rebuild
practices are likely to be minimal since the catalyst, the key
. 4
Page 47
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emission control component in a gasoline engine, is generally not
changed.
Replacement parts are either OEM or aftermarket. As with
heavy-duty diesels, the more complex the component, the more
likely it is going to be rebuilt rather than replaced with a new
part. The choice to use aftermarket or OE parts will be a
question of price and availability. Ford, GM, and the majority
of ATD/NADA members said that they use OE parts, but this is not
surprising given the fact that ATD members are affiliated with
the OE's and might use OE parts in order to assure that the
warranty remains valid on the rebuild. One utility company, on
the other hand, said they use either type of parts in their
rebuilds. The choice as to which type of parts to use will be
treated by the rebuilder in the same way as it is with HDDE's.
6.4 Rebuild Frequency
The overwhelming majority of HDGE rebuilding consists of
rebuilding short and long blocks. HDGE's are generally treated
. the same as LDV and LOT engines, namely they are run until the
engine or truck experiences a major failure and then, if cost
effective, the broken part is fixed. The decision to rebuild a
HDGE is not automatic like it is for HHDDE's. Frequently, the
owner decides to replace the engine. In a 1981 Fleet Maintenance
& specifying (T M & si survey, 42% of fleets stated that they
Page 48
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would replace a .gasoline engine rather than perform an overhaul,
and respondents who said they would overhaul said that their
decision would be case-by-case.*3
It is difficult to state a mileage range at which gas
engines will be rebuilt because owners do not schedule rebuilds.
*
Ninety-five percent of HDGE owners perform rebuilds only when
engine performance dictates.44 The statutory useful life of
these engines is 110,000 miles. The data we have concerning HDGE
rebuilding show that when it does occur, the mileage will
generally be near useful life mileage. The F M & S survey gave
an average of 99,600 miles to overhaul. Only two ATD/NADA
respondents specified when they rebuilt gas.engines, and those
numbers were 65,000 and 100,000 miles. A power company said they
rebuilt gasoline engines in their fleet at 100,000 miles.
Therefore, it is reasonable to believe that gas engines are
rebuilt generally around 100,000 miles. Rebuilds will occur at
different ages because of the varied mileage accumulation rates
within the HDGE class. Few, if any, of these engines will be
rebuilt a second time because these trucks will wear out prior to
the mileage necessary for a second rebuild.
43Fleat Maintenance and Survey. March, 1981.
UIfl.
Page 49
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Chapter 7 - REBUILD MAPyf!T
LlI Truck Population
EPA used three sources of information to determine the most
reliable estimate of the current heavy-duty truck fleet; MOBILE
4.l'5, 1989 Energy and Environmental Analysis, Inc. (EEA) Motor
Fuel Consumption Model (MFC) as prepared for the Department of
Energy*4, and MVMA Facts and Figures*7. The various reports are
not consistent in the way they group light, medium and heavy
trucks and only MOBILE 4.1 separates data up by fuel type and
model year.
A summary of MOBILE 4.1 registration data for the various
classes of engines is shown in Table 7.1 below.
See Appendix E for a model year breakdown of registrations
by fuel type and EPA classification.
Table 7.2 shows the EEA MFC estimates for heavy-duty truck
populations in 1991 and 2000.48
45MOBILE 4.1 Motor Fuel Consumption Model.
"1989 EEA Motor Fuel Consumption Model.
"MVMA Facts 'N Figures 1986-89.
**See note 45. ,
Page 50
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light heavy diesel -1,140,000 trucks
(8 , 5(70-19 , 5 0 0 lbs.)
medium heavy diesel 820,000 trucks
(19,501-33,000 lbs.)
heavy heavy diesel 1,630,000 trucks
(33,001 lbs. and higher)
light heavy-duty gas 2,500,000t trucks
(8,500-14,000 lbs.)
heavy heavy-duty gas 1,500,000 trucks
(14,001 lbs. and higher)
Hlght gu data ara tatimatad.
Table 7.1 - MOBILE 4.1 Truck Registration for 1991
1221 2000
light heavy diesel 910,000 1,675,000
(8,500-14,000 lbs.)
medium heavy diesel 1,000,000 1,500,000
(14,000-50,000 lbs.)
heavy heavy diesel 1,460,000 l,770,000
(50,000 and higher)
light heavy gas 4,100,000 4,450,000
(8,500-14,000 lbs.)
¦»*!
medium heavy gas 1,300,000 860,000
(14,000-50,000 lbs.)
heavy heavy gas 12,000. 1,000
(50,000 and higher)
tEEA doc* not grot*} wafght classification* tha tmm a* NOtlLI 4.1
Table 7.2 - EEA MFC Diesel Registrations for 1991 & 2000
EPA will use the MOBILE 4.1 data to predict fleet
composition because MOBILE data can be broken down by age and
fuel type as shown in Appendix E. This fleet registration data
Page 51
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will be used in conjunction with other data to estimate the
number of rebuilds occurring annually.
1*2 Heaw-Dutv Tmeit Mileage Accumulation
EPA used two sources o£ information to determine mileage
accumulation rates: MOBILE 4.1 and EEA's analysis of the 1987
TrucJc Inventory and Use Survey (TIUS)*9. Mileage accumulation
data is shown in Appendix F. EEA data was only available for
medium and heavy diesels. Note that the weight classifications
are not the same for each source.
EPA will use the EEA data when available because it is based,
on the 1987 TIUS while MOBILE 4.1 is based on the 1982 TIUS. For
those categories in which EEA data is not available, EPA will use
MOBILE 4.1. This mileage accumulation data will be used in
conjunction with other data to estimate the number of rebuilds
occurring annually.
MOBILE 4.1 vehicle miles traveled (VMT's) are shown in
Appendix G. The data are shown as a percentage contribution of
each model year within a given weight class.
49EEA mileage accumulation data derived from 1987 TIUS
Page 52
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7.3 Estimated Annual Rebuilds - HHDDT]'«
Method 1
EPA determined that HHDDE's are rebuilt approximately every
300,000 - 400,000 miles. Using the EEA data in Appendix F,
trucks will typically undergo their first rebuild beginning at
age four. The; second set of rebuilds will generally begin when
the engine is nine years old. The third rebuild will occur
sometime after 15 years. While some engines will accumulate
mileage faster and will be rebuilt more than three times, and
some will be rebuilt less, the average truck should follow this
cycle.
EPA recognizes that not every four, nine and 15+ year old
engine is rebuilt each year and that engines of other ages will
also be rebuilt. While the exact profile-of HHDDE rebuilds per
year is unknown, it is reasonable to believe it looks something
similar to Figure 7.1. This figure is intended to represent a
general distribution of HHDDE rebuilds and is not meant to
reflect the exact shape of the curve. The exact curve is
i#-
unknown. The point demonstrated by this figure is that most
first rebuilds will occur at around four years old, second,
rebuilds around nine years old and third rebuilds after 15 years
old. Also, there should be a greater number of first rebuilds
than second rebuilds, and more second rebuilds than third
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Figure 7.1
HHDDE Rebuild Distribution
10 15
Age of Vehicle
(NOTE: This figure is intended to show a possible distribution
of rebuilds. The actual distribution is unknown.)
-------
rebuilds.
Since there is no accurate method to determine the exact
shape and values of the curve in Figure 7.1, an approximation
will be made to estimate the actual, number of rebuilds. This is
shown as the solid line spikes in Figure 7.1. The height of each
spike is estimated to be the number of trucks on the road of that
particular age because, on average, the four, nine and 15+ year
old trucks are most likely to be rebuilt. The number of trucks
of ages 15-25+ were averaged and the spike located at the
midpoint (20 years). For HHDDE, MOBILE 4.1 estimates that in
1990 there were about 120,000 HHDDE's which were four years old,
65,000 which were nine years old and an average per year of
30,000 which were 15+ years old. Thus, the total estimate of
HHDDE rebuilds per year is about 220,000. This analysis assumes
that every HDDS will eventually be rebuilt. Industry comments
indicate that most first and third rebuilds will be performed in-
frame by owners or fleets. In-frame rebuilds account for more
than 50 percent of all estimated HHDDE rebuilds.
Method 2
A second way to estimate rebuilds is to apply survival
probability and mileage between rebuilds to average annual
production figures. According to MVMA Facts and Figures /88«
there have been an average of 135,000 HHDDE's produced per year
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since 1973.
We know that, on average, the first set of rebuilds will
begin occurring when the engine is about four years old, the
second at nine years old, and the third set after 15 years old.
According to MVMA survival probabilities, 97 percent of HHDDE's
produced in a given year will still be on the road at age four to
five years, 71 percent at age nine years, and 21 piercent after
age 15 years.50 (Note: EPA chose the midpoint probability when
a range of years was given). Applying these probabilities to the
135,000 per year production, we see that 131,000 are still on the
road at the time of first rebuild, 93,000 at the time of second
rebuild and 28,500 at the time of third rebuild for a total of
253,000 rebuilds per year. The approach is illustrated in Table
7.3.
Average
Engines
Produced Age at Likelihood
Per Year Rebuild gMrvlvalt
135,000 4
per year
9
yrs.
yrs.
15+ yrs.
97%
71%
21%
Surviving
Engines
131,000
93,000
28,500
Number of
Rebuilds
Per Year
131,000
93,000
28.500
0»
-253,000
tTM« figurt it the likelihood of survival of tho Midpoint ynr. For thoaidpoint of 9-13 y«r» it
12 ytart. Fifty ptretnt (50*) it thrlikalihood of turvivlna 12 yttrt.
Not*: MVMA probabilities arc for 26,000 lt». and higher 6VW.
Table 7.3 - Estimating Rebuilds Using Survival Probabilities
50See note 46.
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Both methods used to estimate HHDDE rebuilds assume these
engines will continually be rebuilt every 300,000 - 400,000 miles
until retired from use. Although these rebuilds will occur over
15 or more years, they should average out to 220,000 - 250,000
per year. It should be noted that some engines will receive four
or more rebuilds. On the other hand, some engines will undergo
fewer than three rebuilds or will be exported or used in off-road
applications and thus lower the number of on-highway rebuilds.
Based on industry supplied export figures, we do not feel the
numbers are significant enough to affect the estimate of
rebuilds.
Using the expected increase in truck registrations predicted
by the EEA MFC model, we can make a rough estimate as to the
number of rebuilds which may occur in the year 2000. For heavy
diesels, EEA shows about a 21 percent increase in HHDDE
» *y • ¦
population by 2000. Similarly, a 21 percent increase inrthe
number of rebuilds could be expected, thereby increasing the
total to 260,000 - 300,000 rebuilds per year. This assumes that
mileage between rebuilds as described in this report is still
valid in 2000.
¦bt
Using VMT data from Appendix G, we see that 50 percent of
all HHDV VMT's in 1990 were from four year old and newer trucks.
This means that the other 50 percent of HHDV VHT's came from
trucks whose engines have likely been rebuilt at least once.
Page .56
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Similarly, 35 percent of HHDV VMT's in 1990 were from nine year
old and newer trucks. The remaining 15 percent of VMT's are from
trucks whose engines have likely been rebuilt twice. Finally, we
see that only 3 percent of all HHDV'VMT's are from trucks whose
engines have likely been rebuilt three times (15+ year old
trucks).
In summary, about one-half of all HHDDE VMT's are from
trucks whose engines have undergone at least one rebuild, are
past their statutory useful lives, and whose emissions
characteristics are unknown.
7.4 Estimated Annual Rebuilds - MHDDE'a
Estimating MHDDE rebuilds cannot be made using the same two
methods used to estimate HHDDE rebuilds because not all. medium
diesels are continually rebuilt until retired from use.
In order to make an estimate of MHDDE rebuilds, a few points
need to be reiterated. As discussed in Chapter 5, all sleeved
MHDDE's that survive until rebuild age will be rebuilt, however
these engines account for only 30 percent of the population. The
other 70 percent are non-sleeved engines of which an estimated 50
percent will be rebuilt when worm
EPA determined that rebuild age for MHDDE's is about 200,000
Page 57
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miles. Appendix F EEA data shows that MHDDE's reach 200,000
miles after about nine years. MVMA data shows that only 71
percent of MHDDE's will live to be nine years old.51 Using
these percentages along with average annual production figures,
an estimate of MHDDE rebuilds can be made.
EPA production reports show that an average of 145,000
MHDDE's were produced per year52 over the past three years.
(MVMA data was not used because no distinction can be made
between gas and diesel sales as could be done with HHDDE's).
Each year's production introduces about 43,500 sleeved MHDDE's
and 101,500 non-sleeved MHDDE's into commerce. At nine years old
(age of rebuild), about 31,000 sleeved engines and about 72,000
non-sleeved engines will still be on the road. As discussed in
Chapter 5, most, if not all, sleeved engines will be rebuilt and
only 50 percent of the non-sleeved engines will be rebuilt. The
total estimate for MHDDE's rebuilds is then 67,000. This
approach is outlined in Table 7.4.
Using the expected increase in population predicted by the
EEA MFC model, we estimate roughly a 50 percent increase, in the
number of MHDDE rebuilds by the year 2000, thereby increasing the
total to 100,000 per year. This assumes that the ratio of
sleeved vs. non-sleeved engines remains fairly constant and that
51See note 46.
"Based on 1987, 1988 and 1989 EPA heavy-duty production reports.
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P.66
i
mileage between rebuilds as described in this report is still
valid in 2000.
Using VMT data from Appendix G, we see that 85 percent of
all MHDV VMT's in 1990 were from nine year old and newer trucks,
This means that the other 15 percent of MHDV VMT's came from
trucks whose engines may have been rebuilt at ieast once.
Average
Engines Number of
Produced Age at Likelihood Surviving Likelihood Rebuilds
Per Year Rebuild of. Survivalt Engines Rebuild Year
43,500 9 yrs. 71% 31,000 100% 31,000
(sleeved)
101,500 9 yrs. 71% 72,000 50% 36,000
(non-
sleeved)
Total 67,000
t mvma probabilities arc for 26,000 lb«. and higher GVW
Table 7.4 - Estimating MHDDE Rebuilds
7.5 Estimated Annual Rebuilds - LHDDE'S
According to MOBILE 4.1 (Appendix E), there were
approximately 1,140,000 LHDDE's in operation in 1990. MOBILE 4.1
mileage accumulation for these engines is shown in Appendix P.
Comments were received from several OE manufacturers regarding
LHDDE rebuilding.
Page 59
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As discussed earlier, EPA determined that most LHDDE's are
*
rebuilt because of engine failure. This claim is supported by
the fact that manufacturers sell far more short blocks than
complete engines, in fact, some OE manufacturers do not sell or
authorize anyone to sell complete LHDDE's. These OE's feel there
is no market for complete engines. Sales figures supplied by
OE's indicate that very little LHDDE rebuilding • actually takes
place.
One major OE did not submit any comments on rebuilding of
it* s products, however, it is expected that the total number of
LHDDE rebuilds would still be very small even with this
additional data.
Because LHDDE's are generally not rebuilt, it was not
possible to quantify the age or mileage at which rebuild is
likely to occur. Therefore, estimates of annual rebuilds using
the methods of the previous sections will not be made.
Due to the small number of rebuilds on LHDDE's and the
relatively low mileage accumulation rate for these vehicles as
shown in Appendix G, EPA feels the VMT's traveled by rebuilt LHDD
engines is very small.
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I
7.6 Model Years of Heavy Diesels Being Rebuilt
Heavy-duty engines from the 1970's, 1980's, and 1990's are
currently being rebuilt. Diesel engines of the early 1980's are
currently the most frequently remanufactured engines while diesel
engines of the mid-late 80's are the most frequently rebuilt by
owners and shops. Similarly, by the year 2000, EPA expects that
engines of the early-mid 90's will be rebuilt most frequently.
EPA received data from OE's, independents, trade
associations and fleets regarding the model years of engines
currently being rebuilt. In largie part, these data agree with
EPA's findings concerning the age at which the various categories
of engine are rebuilt.
Large groupings of HHDDE rebuilds are currently being
performed by 0E's on engines of the early 1980's vintage which
corresponds to when the first out-of-frame rebuild is likely to
occur (at around nine years old). Fleets showed a similar
pattern but with more late 1980's engines being rebuilt. This
agrees with our finding that most first rebuilds are performed on
engines which are around four years old. Independent reb'ftilders
shoved an almost flat distribution of rebuilds among model years.
It should be noted that all groups reported rebuilds of engines
as far bacfc as the 1960's and 1970's vintages.
Page 61
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For MHDDElarge groupings of OE rebuilds were reported
for engines of the early 1980's. This agrees with EPA's findings
that MHDDE*s are rebuilt at about nine years old. Data specific
to MHDDE rebuilding were not provided (or at least broken down)
by other industry groups.
Zil Estimated Annual Rebuilds - HDGE's
We estimate, based on MOBILE 4.1, that there are
approximately 4,000,000 heavy-duty gas trucks in operation in
1990 (light heavy-duty and heavy heavy-duty combined). The
mileage accumulation profile for HDGE's is shown in Appendix F.
EPA received comments from major OE's and trade associations
relating to rebuilding of heavy-duty gasoline engines.
As discussed earlier, HDGE's are generally rebuilt because
of engine failure. This claim is supported by the fact that
manufacturers sell, far more short and long blocks than complete
••J'-.*
engines. In fact, some major OE's do not sell any complete
remanufactured gasoline engines.
AERA, as well as a major OE, stated that aside from'the OE's
and their authorized remanufacturers, not much HDGE rebuilding or
remanufacturing occurs. The majority of rebuilds are performed
by OE dealers or others using OE parts. Based on the available
data, EPA estimates only 40,000 HDGE's are rebuilt each year
Page 62
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I
(about one percent of the total population of HDGE's).
Because of the small number of rebuilds on HDGE's and the
relatively low mileage accumulation rate for these vehicles as
shown in Appendix G, and the lacJc of emissions critical parts
affected by rebuild, EPA feels the emissions impact of HDGE
rebuilding is small, and any further study should center on
heavy-duty diesel engines.
7.8 Model Years of Heavy Heaw-Dutv Gasoline Engines Being
Rebuilt
The only data EPA received relating to model years of HDGE's
being rebuilt was supplied by an independent remanufacturer. The
data supports the claim that gas engines and partial blocks are
rebuilt primarily to replace failed units, especially when the
failed unit has not accumulated significant mileage. The highest
number of rebuilds occur in the 1986-1990 timeframe, and
according to MOBILE 4.1, HDGE's will only have 20,000 - 80,000
miles accumulated.
Page 63
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P.71
Chapter 3 - Emissions from Rebuilt Engines
8.1 Emissions Impacts of Rebuilt Gasoline Engines
No emissions data relating to rebuilt gasoline engines was
provided in response to EPA's Federal Register Request for
Information. However, EPA believes any emissions impact that may
result from rebuilding heavy-duty gasoline engines to-be very
small. This conclusion is based on two key qualitative factors.
First, very few heavy-duty gasoline engines are rebuilt.
These engines comprise the majority of the on-highway heavy-duty
market, yet by far account for the fewest number of rebuilds.
See Chapter 6 for a discussion of gasoline rebuilding practices.
Further, gasoline engines accumulate mileage slowly relative to
the larger diesel engines, so any excess emissions which result
from rebuilding would make a small annual contribution to air
pollution. EPA did not attempt to determine the vehicle miles
traveled by rebuilt, heavy-duty gasoline vehicles, however, we
believe the mileage to be very low.
Second, the components most often replaced during rebuild
(short and long block) are not considered key emissions control
components of a gasoline engine* Those components, such as
carburetors and catalysts, are usually reinstalled on the engine
during rebuild without servicing. EPA- believes that the
Page 64
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emissions after-rebuild should be similar to the pre-rebuild
emissions.
8.2 Emissions Impacts of Rebuilt Diesel Engines
Only one respondent, an OE manufacturer, supplied data
relating to emissions from rebuild heavy-duty diesel engines.
Five high mileage engines were subject to a basic engine tune-up
and baseline tested for HC, CO, NOx, and smoke emissions. The
as-received mileage on each engine ranged from 220,000 - 570,000
miles. After the baseline test, each engine was remanufactured
by the OE using new emissions related components (fuel pump,
cylinder kits, turbocharger, and puff limiter) and a combination
, «
of new and rebuilt parts for other engine systems.. After a 25
hour break-in period, each engine was retested. Results varied
for each.engine and each pollutant; some engines produced less
emissions after rebuild while other produced more. However,
emissions from each engine remained below the 1985 Federal
standards after rebuild. The highest mileage engine (570,000 in
use miles) showed the only across-the-board reduction in
emissions.
A basic assumption within the heavy-duty industry is that a
properly rebuilt engine will have emissions similar to those of
new engine of the same model year*. This belief is widespread
among rebuilders and stems from the theory that if every part of
Page 65
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an engine is brought back into specification with OE or 0E-
equivalent parts, there is no reason why the engine should not
have like-new emissions.
A 1987 CARB study on engine rebuilding also assumed "that a
properly rebuilt engine will emit at levels close to" new engine
levels53 and the rate of emission deterioration will be the same
for new and rebuilt engines. The exception to this would be from
incorrect rebuilds in which the emissions immediately after
rebuild would be higher than those of a new engine and would
deteriorate at approximately the same rate.54 In this case,
"incorrect rebuild" meant either incorrect part replacement (i.e.
wrong part number) or incorrect parameter settings.
The information available to EPA suggests that incorrect
part replacement should not be a significant problem. As
discussed in Chapter 5, most rebuilders build to original
calibration using proper replacement parts. Although CARB did
determine.rates at which certain parts are incorrectly replaced,
the rates were very low. It was determined that although
incorrect rebuild practices mav have an impact on emissions, this
impact is not estimated to be significant.55 CARB determihed
53See note 21.
54Id.
55Xd.
Page 66
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that 80 percent*of HC increases and 66 percent of Nox
increases56 from rebuilds were attributable to improper
calibration of components by installers and owners and not a.
direct result of poorly manufactured parts or of the actual
rebuilding of engines.
The notion that maintenance and calibration play a large
role in actual engine emissions was also raised by AERA.
Comments received from AERA stated that high levels of emissions
can be "directly related to on-going engine, engine management
and fuel system maintenance".57
The OE information and the data described in the CARB report
are useful; however EPA feels that because of the large number of
heavy-duty diesel rebuilds that occur and the high mileages these
vehicles accumulate, more emissions data are needed. Data which
show comparisons between rebuilds performed by different sectors
of the industry, as well as data which show the impact of in-
frame rebuilding practices, will better serve to determine the
effect of rebuilding on engine emissions.
8.3 EPA Testing
Because of the lack of available emission data pertaining to
56ia.
57See note 28.
Page 67
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P-75
rebuilt engines, EPA will conduct limited testing of these
engines. EPA testing will focus on HHDDE's and MHDDE's, as these
engines are rebuilt most frequently. Furthermore, rebuilt
engines within these categories account for a substantial portion
of all vehicle miles traveled by these groups.
»»
Page 68
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P. 76
1 Rp!l(
si«r
No. 63 / Th
jr.sduv. April 4. 19^1 / Wices
i:3:j
; ; •: in;
. : . :n U-K
r : '41 ."notions to intervene,
if r.terver.tion. requests for
procedures. and written
sr.ouid be filed with ;he
0:fi :e of Fuels Programs at the addresj
:">tcd above.
It :s ia:cnded that a decisional record
¦n the application will be developed
through responses to this notice by
parties, including the parties' written
comments and replies thereto.
Additional procedures will be used as
necessary to achteve a complete
understanding of the facts and issues. A
party seeking intervention may request
that additional procedures be provided,
such as additional written comments, an
oral presentation, a conference, or trial-
type hearing. Any request to file
additional written comments should
explain why they are necessary. Ar.y
request for an oral presentation should
identify the substantial question of fact
Uw, or policy at issue, show that it ia
material and relevant to a decisioin in
the proceeding, and demonstrate why an
oral presentation is needed. Any request
for a conference should demonstrate
why the conference would materially
advance the proceeding. Any request for
a trial-type hearing muat that that therv
are factual issues genuinely in dispute
that are relevant and material to a
decision and that a trial-type hearing ia
necessary for a full and true disclosure
cf the facts.
If an additional procedure ia
scheduled, notice will be provided to all
parties. If no party requests additional
procedures, a final opinion and order
.T.a> be issued based on the official .
record, including the application and
responses filed by parties pursuant to
this notice, in accordance with 10 CFR
330.318.
A copy of TCGM's application is
available for inspection and copying in
the Office of Fuels Programs Docket
Room, room 3F-058 at the above
address. The docket room is open
between the hours of 8 a.m. and 4:30
p.m.. Monday through Friday, except
Federal holidays.
Issued in Washington. DC on March 28.
1901.
Clifford P. TomaaMwtkif
A ct;nt Deputy Assistant Secretory for Fuels
Programs. Office of Fossil Energy. ¦
IKR Doc 91-?MS Filed 4-4-«1i 8:49 «m|
E?iViflONMENTAL PROTECTION
AGENCY
fRL-3917-41
Request for Information Concerning
Heavy-Outy Engirt* Rebuild Study
agency? Environmental Protection
Agency.
action: Notice, request for information.
summary: As required by the Gean Air
Act Amendments of 1990. the Agency
has begun a study of heavy-duty engine
rebuild practices and the impact these
practices have.oaengine emissions. This
study will assist the Agency in
determining whether regulations
governing rebuilding practices are
needed. To aid the Agency in conducting
this study. EPA requests written
submissions from all interested partiee
who wish to comment on heavy-duty
engine rebuild practice*, the impact of
these practicea on engine emiasions. and
any other related aspects of the heavy-
duty truck market
oatu: Comments from interested
parties should be received no later than
Stay 8.1991.
AOOftittU: Written comments should
be sent to: Environmental Protection
Agency. Manufacturers Operations
~ivison (EN-MQf), Attn: Kari Simon,
401 M SU SW„ Washington, DC 2040ft
FO« FUKTHOI MMWUTWM CONTACTS -
Karl Simon, at the addiesa given above;
telephone (202) 382-23ia
SUmnMNTAL MPONMATIOtC
L Introduction
Section 202(e)(3)(D) of the dean Air
Act as revised by th* Clean Air Act
Amendments of 19901 require* EPA to
study th* practlca of heavy-duty engine
rebuilding and Its impact on engine
emissions. On the bains of such study
and any other pertinent Information, tha
Administrator may prescribe any
requirements to control rebmilding
practices, including standards for
emissions from rebuilt heavy-duty
engine* which cause or contribute to air
pollution which may be reasonably
anticipated to endanger public health of
welfare, taking costs into account
The EPA Office cf Mobile Source*.
Manufacturers Opt re'Jons Division, has
begun a study of heavy-duty engine
rebuilding practices. For the purpose of
this study, e heavy-duty engine is on*
used in e heavy-duty vchid* as defined
at 40 CFR S&062-X This definition .
includes, in general, tracks with a po«
vehicle weight rating (GVWR) greater
than 8.300 pounds. The results of this
study, along with any other availablo
information on this topic, will form th*
b.is.j for \S? dr.'er:n:.t.- " ¦
whether further ti> T.\ >ui..- ¦ ,
regulations or guidelines. :j wO.-:.vji
enxine rebuilding practices is needed.
Among the information sought through
this request for information are data on
the nature of the heavy-duty rebuilding
industry, the volume of heavy-duty
rebuilding occurring annually, the
parties involved in rebuilding and in the
manufacturing of parts used bv
rebuilders. the nature of rebuilding
practices, and the costs associated with
all aspects of this industry. EPA also
plans, as part of this study, to conduct
emissions testing of different heavy-duty
engines in various rebuilt stages. Data
generated from these tests will be used
to determine tha air quality impact of
rebuilt engines.
Some of tha questions posed in this
request for information may ask for
information that may be considered
confidential business information by a
company wishing tarespond to the EPA.
Submitting parties may assert a
business confidentiality claim covering
all or part of tho information provided in
response to this request To assert a
business confidentiality claim regarding
any of th* information, you should do so
in a manner consistent with 40 CFR
2J03(b). Information covered by such a
claim will be disclosed by EPA only to
the extent and by means of the
proceduree set forth in 40 CFR part 2.
subpart B. If no claim accompanies the
information when it is received by EPA.
it may be made available to the public
without further notice to the submitting
party.
Question*
Pleas* indlcat* th* questions you are
responding to in your response^
Whenever possible, please break down
response* into th* following two
categories
a. Pud type
1-gas.
ZdieseL
b. Vthicl*/engin* class
IOB (MOO < GVWR s 10.000
lb*). »»
2. das* HI (10.000 < GVWR < 14.000
lbs).
3. Class IV (14000 < GVWR < 18.0U)
lbs).
4. Class V (1M00 < GVWR < 19.S00
tbek
5. Class VI (19J00< GVWR < 28.000
Ibsh
& Class VH (2&000 < CVWR < 33.000
,bi* •
7. das* vm (CVWR > 33JOO lbs).
Interacted parti** are invited to
address any question of fact law, or
polley which th*y fed may have a
APPENDIX A-i
-------
I3.12S
Federal Register / Vol- 30. \'o. 5.5 / Thur-ridV. April 4.
1991 / Sof.ce3
¦ ¦ - i ¦ r. ".e r- iw d.-'v ens Tie
-»t s-..J> anci :s -at eefiressod tn
:-o questions beicw.
1. i^'eise describe your crganizaiion
13. Whet engine ports eouUbn
sppnded and inrh triad In a rstrnflt ktff
What parte oeuld net be apgradadT
14. Do yon hav* any ewissiuiiB lest
data relating to engine nbefldi&g? ff yen.
plana* provide.
11 Aseaning (hat regulation of enginn
rebuildfaf prectioea wil oocv. whet
••PRl 3919-41
Availability of Testing Manual
aocmct Environmental Protection
Agency.
Action: Notice of Availability of
Document entitled "Evaluation of
Dredged Material Proposed for Ocean
Disposal-Testing Manual."
suMnuav: This action announces the
availability of the revised testing
manual entitled "Evaluation of Dredged
Material Proposed for Ocean Disposal-
Testing Manual." Copies of the manual
can be requested by writing to the
address listed below under
"AOOniMCT.
: A copy of "Evaluation of
Dredged Material Proposed for Ocean
Disposal-Tea ting Manual" and/or the
initial mixing model disks can be-
obtained by writing to Ms. Billie
Skinner. UiL Amy Corps of Engineers.
Waterways Experiment Station. EP-D.
3009 HaHs Ferry Road. Vicksburg,
Mississippi 39180-6198.
ran funran nvonatATioN conacR
David ladtud. Mail Coda WH-5MF.
Marine Penults Monitoring Bwwfc
UJ. Envisonmental Pro taction Agency
401M Street SW„ Washington. DC
20OD (phone (202) 475-717B]; or Da vid
Meddt. Office of Environmental Policy,
CECW-fO, OS Amy Corps of
Engines!. 20 Massachusetts Ave. NW..
Washington. DC ABM (pbona (202) 277-
8843).
operaflons involving tha dumping of
dredged materials into ocean water*
must be evsftiatad to deteiiuina the
potential environmental impacts of such
acttvMeo. TMs is don* as pert «f Urn
permitting piouias under title I of flw
Marine ftotacflon. Research. end
Sencauriae ActfPeb. L B-U3
[A#tSAft.ls accordance with section
108 of the li#ISA. the Corps of
Engineers (CE) Is the permitting
authority, wi*Jhe daiaminntian to
isene a pan* being subject to nviaw
Dated March atftt.
tA^aiaittidaeforAir and
lHM«44lilttnt|
by
(EPA). The MFBSA pnvides that tha CE
uh umjBualil criteria developed by
EFAundar section 102 of the Act in
makingpemit and project dacisiona.
Tha criteria developed by EPA under
section 103 of tha MPRSA an printed at
r e-Z*. In order to
regulate*and advene ecological
effects of ocean dvping at dredged
tnafisl the rsgslatinm trr1"""
valuetive las bilnuss such a* toxicity
and liliianrsmalsltna bioaaaays. whi<±
provide relatively dinct estimatss of the
potential for environmental impact
-------
Appendiv 7^
1. Alabama Power — investor-owned electric utility company
2. American Trucking Associations, Inc. (ATA) — industry
association
3. Automotive Engine Rebuilders Association (AERA) - industry
association
4. Automotive Parts Rebuilders Association (APRA) — industry
association
5. California Air Resources Board (CARB) — state regulatory
agency
6. Caterpillar, Inc. —¦ Original Equipment (OE) manufacturer
7. Council of Fleet Specialists (CFS) ~ industry association
8. Cummins Engine Company, Inc. —- OE manufacturer
9. Dealers Manufacturing — independent remanufacturer
10. Department of the Army, U.S Materiel Command — manages
equipment and vehicles for the Army
11. Detroit Diesel Corporation (DDC) — OS manufacturer
12. Donaldson Company, Inc. —- manufacturer of aftertreatment
devices
13. Engine Control Systems — manufacturer of aftertreatment
devices
14. Engine Manufacturers Association (EMA) — industry
association
15. . Enginetech, Inc. — manufacturer and distributor of engine
components
16. Federal-Mogul Corporation — manufacturer of OEM and^
replacement parts
17. Ford Motor Company (Ford) — OE manufacturer
18. Fred Jones Manufacturing Company — independent
temanufacturer
19. General Motors Corporation (GM) — OB manufacturer
m
20. Heavy Duty Manufacturers Association — industry association
Appendix B-i
-------
Apppndix B
20. Heavy Duty Manufacturers Association ~ industry association
21. Jasper Engine and Transmission Exchange (Jasper) —
independent remanufacturer
22. Mack Trucks, Inc. (Mack) — OE manufacturer
23. Manufacturers of Emission Controls Association (MECA) —
industry association
24. American Truck Dealers Division of the National Automobile
Dealers Association (ATD/NADA) — industry association
25. National Engine Parts Manufacturers Association — industry
association
26. National Institute for Automotive Service Excellence (ASE)—
industry association
27. Production Engine Remanufacturers Association (PERA) —
industry association
28. The Tucker Co., Inc. — manufacturer and distributor or
engine components *
Appendix B-ii
-------
TAJLE 5-6
SUMMARY OF REBUILD
COMPONENT SERVICING PRACTICES
IN-FRAME
FLEET SURVEY (Survey #3)
(% DISTRIBUTION)
Replaced
Replaced
Mot
Serviced
Original
Psrt
Rebuilt
With
Rebuilt
Parts
Replaced
With Rev
OEM Psrts
With New
Afteraarket
Saaple
Size
Piston Rings
2
0
0
93
S
42
Cylinder Liners
7
•
0
0
8t
* " 3 .
42
Piscons
7
2
2
13
42
Cylinder Heads
0
43
40
10
L . 3
42
Fuel Injectors
0
43
38
14
3
42
Injection Punp*
5
SO
29
U
S
42
Governors or Fuel
Daisy Mechanisas
9
sa
24
IS
3
34
Turbochargers
2
3»
4J»
12
3
42
Aftsreoolers
• .
56
24
i <*
3
39
Roots Blowers
4
50
27
IS
26
iocker Araa
12
39
27
20
41
-------
TA3L£ 5-7
Piston Rings
Cylinder Liners
Piston*
Cylinder Heads
Fuel Injector#
Injection Fuape
Turbochergers
Aftareoolers
Roots Blower*
Rocker Aras
SUMMARY OF REBUILD
SERVICING- PRACTICES
OUT'OF-FRAME
FLEET SURVEY (Survey »3) .
(% DISTRIBUTION)
Original
Not Pert
Sarvtead .
0
Or
0
0
0
0 .
0
0
40
43
SO
a
59
44
30
Replaced
Vleh Replaced
Rabuile
0
0
2
43
43
3«
33
2C
31
2t
Raplacad
With New
With New Aftaraarket Sanpla
nvx Psrta fl»> _£iH-
95 3
95 3
93 3
12 3
10 . .. 2
10 2
IS 2
ia J
U i 4
1» ; 2
42
42
42
42
42
42
40
39
21
40
-------
4
t
i , i J
H.S?
i
7A3LE 5-8
SUGARY OF REBUILD
COMPONENT SERVICING PRACTICES
IN-FRAME
REBUILD SHOP SURVEY (Survey «4)
(t DISTRIBUTION)
Not •
Serviced
Original
P*rt
Rabuile
Replaced
VI eh
Rebuilt —
Parts
Replaced
Vith Nov
Replaced
With New
A/cenurkee
?»rti
Staple
Slza
Piston Rings
0
0
0
100
0
47
Cylinder llniri
0
0
2
9t
0
47
Pistons
0
0
2
9t
0
47
Cylinder H««ds
0
17
6t
13
0
47
fuel Injectors
0
11
72
17
0
47
Injection ?\spa
It
24
S3
4
0
45
Covtnori or Fuel
Do ley Mechanisms
9
».
« ;
30
13
0
46
Turbochergers
2
11
•
7t
•
7
0
45
Aftereoeler*
It
33
27
22
0
45
Roots Blowers
2
35
3t
7
0
40
Rocker Armm
13
22
41
24
0
46
J
4
-•
«
»»
•
Appendix C-lit
-47-
-
-------
TABLE -5-9
Su7«AAY OF REBUILD BEHAVIOR
COMPONENT SERVICING
OUT-OF-FRArtE
REBUILD SHOP SURVEY (Survay »4)
(* DISTRIBUTION)
Replaced Replaced
Origin*! With Replaced With New
Hoc
Serviced
Pare
R.buile
Rebuilt
Pares
VIch New
OEM Parts
Afcarnarkae
Parts
Sampla
Slzt
Piscon Rings
0
0
0
100
0
47
Cylinder Liners
0
0 "
2
98
" ~o
47
Piscon*
0
0
2
98
0
47
Cylinder Head*
a
19. ..
. 64 ••
17
..
47
Fuel Injector*
o-
9
77
13
0
47
Injection Puape
0
23
66
11
0
47
Turbochargers
0
11
81
9
0
47
Aftercoolera
0
39
39
20
2
44
Roocs Blowers
0
3t
51
10
0
39
Rockar Aru
0
20
30
30
0
46
»»
Appendix C-iv
*•-
-------
Sleeves \ew
Pistons. Pins & Lock Rings New
Piston Rings New
Rod Bushings New
Connecting Rods P.emfg.
Rod Bolts & Nuts New
Connecting Rod Bearings Mew
Camshaft Remfg.
Camshaft Bearings „ New
Cam Followers, Rollers, Bushings & Pins New
Cam Thrust Washers New
Crankshaft Remfg.
Main Bearings New
Crankshaft Thrust Washers New
Valves, Springs, Seats & Guides New
Rocker Arm Shafts New
Blower ' Remfg.
Turbocharger Remfg.
Governor Remfg.
Air Compressor* Remfg.
Injector Tubes New
Fuel Supply Pump Remfg.
Fuel Injector Pump Remfg. -
Fuel Injectors Remfg.
Fuel Lines New
Accessory Drives Remfg.
Hoses & Fittings New
Lines & Belts New
Water, Oil & Fuel Filters New
Oil Pump Remfg.
Water Pump Remfg.
Flywheel Remfg.
Gaskets A Seals New
Starter Ring Gear New
Vibration Oamper New or Remfg.
Thermostats New
Idler Gear Bearings New
-------
P-85
LHDGE Registrations as of 7/90 (MOBILE 4.1)
1400 i
TTh
thousand
trucks
in
1 2 343471 9 10 11 12 13 14 13 1C 17 1* 13 20 21 22 23 24 25
Age of Truck
Appendix B-i
-------
HHOGE Registrations as of 7/90 (MOBILE 4.1)
thousand
trucks
1 2 343 (79 9 10 11 12 13 14 13 1« 17 18 19 20 21 22 23 24 23
Age of Truck
-------
f
LHDDE Registrations as of 7/90 (MOBILE 4.1)
thousand
trucks
180
160
140
120
100
80
¦
II
1 II
I ¦
II
1 ¦
¦¦¦¦
4-
IHBHi
-
¦ **'
¦
; f
1 2 3 4 S C 7 • 9 10 11 12 13 14 IS 1( 17 II 19 20 21 22 23 24 25
Age of Truck.
Appendix B-iii
-------
MHDDE Registrations as of 7/90 (MOBILE 4.1)
120 t— ;
100
80
thousand 6q
trucks
40
20
0
123 4 9(78 9 10 11 12 13 14 15 14 17 It 19 20 21 22 23 24 25
Age of Truck
-------
HHDDE Registrations as of 7/90 (MOBILE 4.1)
160,000
140,000
120,000
thousand
truclcs
100.000
80,000
60,000
40,000
20,000
12345(78 » 10 1112 13 1415 l« 17 18 19 20 21 22 23 24 25
Ag« of Truck
-------
HDG Mileage Accumulation (MOBILE 4.1)
200,000
180,000
160,000
140,000
120,000
100,000
80,000
60,000
40,000
20,000
0
.¦hi
lllll
llllllll
minimi
imiiimm
S € 7 » 9 10 11 12 13 14 IS 1« 17 II 19 20+
Age ot Vehicle (years)
B miles/year Bcummulative
-------
P.91
' ' i ' «
200/000
180,000
160,000 -
140,000 ¦
M
i
120,000 -
1
100,000 -
e
s
' 80,000 -
60,000 ¦
40,000 ¦
20,000 -
LHDD Mileage Accumulation (MOBILE 4.1)
IIIIIIIIIIIIIIII
IIIIIIIIIIIIIIIIII
i i rrrrrFPMPPPMMi
1 l 3 4 S < 7 8 » 10 11 12 13 14 IS 1< 1? 18 19 20+
Age of Vehicle (years)
¦ miles/year ¦ Cunnulative
Appendix P-ii
-------
» »
MHDD Mileage Accumulation (MOBILE 4.1,class 6,7 &
8a)
M
i
1
e
s
500,
450,
400,
350,
300,
250,
200,
150,
100,
50,
000
000
000
000
000
000
000
000
000
000
0
TTI
. ¦ I
. I
. I
llll
Illllll
rrrrrrPF
iiiii
1 2 3 4 5 6 7 I ) 10 11 12 13 14 19 1« 17 18 19 20+
Age of Vehicle (years)
¦ miles/year B Cumnulative
-------
P-93
' «
900,000
800,000
700,000
600,000
M
i
500,000
1
e
400,000
s
300,000
200,000
100,000
HHDD Mileage Accumulation (MOBILE 4.1, class 8b)
.¦ 11111
. I
II
llll
111111
mini
rrrrrPFF
5 < 7 8 9 10 11 12 13 14 19 16" 17 It 19 20+
Age of Vehicle (years)
B miles/year B Cummulative
Appendix F-iv
-------
P-94
EEA MHDD Mileage Accumulation (class 6 4 7)
350,000
300,000
250,000
M
i 200,000
1
e 150,000
s
100,000
50,000
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Age (years)
¦ cummulative I miles per year
%
-------
»
• < ,
EEA HHDD Mileage Accumulation (class 8)
M
i
1
e
s
1,000,000
900,000
800,000
700,000
600,000
500,000
' 400,ooa
300,000
200,000
100,000
0
n 11111111111111111
nnnmiiMMMMj
1 2 3 4 5
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Age (years)
Cummulative I miles per year
-------
Travsi ^"¦Taction (VMT) as of Jan. 1, 1990
(ccnnriSucion of a given MY wichin each weight class) >
Model Year
2HDV
LHDV
MHDV
HHDV
HDGV
90
0.00%
0.00%
0.00%
0.00%
0.00%
89
17.10%-
19.80%
17.10%
17.20%
11.90%
88
15.20%
16.90%
15.20%
. 15.20%
11.20%
87
10.20%
10.90%
10.20%
10.20%
9.10%
8 6
10.00%
10.30%
10.00%
10.00%
8.70%
85
11.20%
11.10%
11.20%
11.20%
8.70%
84
9.40%
9.00%
9.40%
9.40%
7.90%
83
5.10%
4.70%
5.10%
5.10%
5.80%
82
4.10%
3.70%
4.10%
4.10%
4.50%
81
2.90%
2.50%
2.90%
2.90%
3.50%
80
3.20%
2.60%
3.20%
3.20%
2.80%
79
3.30%
2.60%
3.30%
3.30%
5.50%
78
2.20%
1.70,%
2.20%
2.20%
4.30%
77
1.70%
1.20%
1.70%
. 1.70%
3.60%
76
0.70%
0.50%
0.70%
0.70%
2.60%
75
0.70%
0.50%
0.70%
0.70%
1.90%
74
0.80%
0.50%
0.80%
0.80%
1.60%
73
0.80%
0.50%
0.80%
0.80%
1.70%
72
0.50%
0.30%
0.50%
0.50%
1.10%
71
0.30%
0.20%
0.30%
0.30%
0.80%
70
0.20%
0.10%
0.20%
0.20%
0.60%
69
0.20%
0.10%
0.20%
0.20%
0.60%
68
0.10%
0.10%
0.10%
0.10%
0.40%
67
0.10%
0.00%
0.10%
0.10%
0.30%.
66-
0.20%
0.10%
0.20%
0.20%
0.70%
where: HDGV - heavy duty gas vehicle (all classes)
< 2HDV - class 2B HDOV
LHDV - class 3 - 5 HDDV
MHDV - class 6 - 8a HDDV
HHDV - class 8a and above
»>
Appendix G
------- |