Bulletin No.:

Service Bulletin

Date:

18-NA-073
December, 2022

INFORMATION
Subject:

Repair Guidelines for Engine Component Wear

Brand:

Model:

GM Passenger Cars and
Trucks

Model Year:

VIN:

from

to

from

to

2015

2023

All

All

Engine:

Transmission:

All

—

Involved Region or Country

North America, Argentina, Brazil, Bolivia, Chile, Colombia, Ecuador, Paraguay, Peru,
Uruguay, Venezuela, Europe, Uzbekistan, Middle East, Iraq, Israel, Palestine, Japan,
Cadillac Korea (South Korea), GM Korea Company, China, Philippines, Egypt, Other
Africa

Condition

Whenever engines have been disassembled, technicians may encounter some visible
engine wear characteristics on critical engine components. Some technicians may be
replacing engines instead of repairing and replacing worn components as needed.

Cause

These conditions may be caused by the vehicle duty cycle, dust in the environment the
vehicle is being operated in and local fuel quality. In some instances, service personnel
may be improperly diagnosing normal engine wear.

Correction

Review the following graphic examples and information in this bulletin.

Information
The purpose of this bulletin is to assist the service
personnel with graphics and information to use as
guidelines in order to perform the necessary engine
repairs and prevent unnecessary engine replacement.
Important: Prior to component replacement: Refer to
SI to diagnose and identify the root cause of the original
failure. In cases involving suspected bearing failure,
remove and inspect the oil filter. Refer to the Oil Filter –
Inspect for Excessive Debris section in this bulletin.
Important: Prior to completing repairs, do a cost
analysis; in some instances, an engine replacement
may be considered.
Important: If SI diagnosis leads to an inspection of the
cylinder bores and reveals cylinder wall damage (i.e.
excessive scoring or out-of-round), an engine
replacement may be required. Refer to the Cylinder
Bore section in this bulletin.
Camshaft
Review the following:

Copyright 2022 General Motors LLC. All Rights Reserved.

4994025

Example of minor scratching/scoring visible on
camshaft lobes and/or camshaft bearing journals. In
this example, the scored components can be replaced
without need for engine assembly replacement.

Page 2

December, 2022

Camshaft Bearing Caps
Review the following:

4991477

Example of minor scratching/scoring visible on
camshaft bearing caps. In this example, the scored
components can be replaced without need for engine
assembly replacement.
Connecting Rod End Caps and Bearings
Review the following:

4992132

Example of minor scratching/scoring visible on
connecting rod bearings. In this example, the scored
components can be replaced without need for engine
assembly replacement.

Bulletin No.: 18-NA-073

Bulletin No.: 18-NA-073

December, 2022

Page 3

Crankshaft in Crankcase
Review the following:

4990880

Example of minor scratching/scoring visible on
crankshaft. In this example, the scored components
can be replaced without need for engine assembly
replacement.
Crankshaft Main Bearings and Journal
Review the following:

4986379

Example of minor scratching/scoring visible on
crankshaft. In this example, the scored components
can be replaced without need for engine assembly
replacement.
4985936

Page 4

December, 2022

Crankshaft, Reluctor Ring and Journal
Review the following:

Bulletin No.: 18-NA-073

Cylinder Bore
Review the following:

4986393

4992739

4990640

Example of minor scratching/scoring visible on
crankshaft. In this example, the scored components
can be replaced without need for engine assembly
replacement.

Bulletin No.: 18-NA-073

December, 2022

5788552

Page 5

5788569

Example of minor scratching/scoring visible on cylinder
wall. In this example, if you cannot catch a pick or
fingernail on the scratch, the cylinder bore/engine block
does not require replacement. If the piston is slightly
scored, the scored piston can be replaced without need
for engine assembly replacement.
Cylinder Out-of-Round
Review the following:
Suspecting an engine block of possible cylinder bore
damage, scoring or out of round as the possible cause
of engine oil consumption, misfire, cylinder leakage or
blow by.
Note: The peak to valley suspecting an engine block of
possible cylinder bore damage, scoring or out of round
as the possible cause of engine oil consumption,
misfire, cylinder leakage or blow by. spec for
crosshatch is .65-2.8 microns. Any deviation and the
crosshatch will be gone even if a cylinder is suspected
of being oversize, we can only confirm that by checking
with an air gauge at the engine plant.

5788571

Page 6

December, 2022

When inspecting the engine block to determine if the
cylinder bores are good, look for the following:
1. Cylinder damage or scoring – The cylinder walls
will contain grooves deep enough to catch with a
fingernail.
2. Out of round cylinder bore – Contains areas where
the crosshatch is missing or worn from different
sections of the cylinder bore. If there is crosshatch
all the way around the bore from top to bottom, the
cylinder bore is not out of round.
3. Dirt intrusion – If the filtering system has been
compromised, the engine will wear out very
quickly. You will find grit in the intake runners and
the cylinder bores will look lightly sand blasted.
The crosshatch will be faint and there will not be
sharpness. At high mileage this may not be
Warrantable if the air filtering system has been
opened numerous times for service in dusty
climates.
4. Catalytic converter failure – If a converter fails and
the brick is broken, the dust can be drawn back
into the engine. A block showing this type of failure
will have bores that look to be sand blasted. Back
cylinders go first if caught early. Otherwise there
will be no crosshatch and the engine will need to
be replaced.
Cylinder Bore Honing Marks
Review the following:

Bulletin No.: 18-NA-073

4993544

Some technicians may be replacing entire engine
assemblies due to marks found at the top of the
cylinder bore. These marks are considered normal and
are left as a result of a manufacturing laser honing
process. DO NOT replace the cylinder block or the
engine for these normal laser honing marks (refer to
PI0725B).
Piston
Review the following:

4993413

4992916

Bulletin No.: 18-NA-073

December, 2022

Page 7

Example of minor scratching/scoring visible on piston.
In this example, inspect for broken and/or stuck rings
and piston ring lands and cylinder wall for damage. If no
cylinder wall damage or other significant damage,
components can be replaced without requiring an
engine assembly replacement.

Oil Filter — Inspect for Excessive
Debris
In cases involving suspected bearing failure, remove
and inspect the oil filter for excessive debris and
damaged pleats. Use the inspection as an indicator of
the amount of material that is displaced through the
engine and lubrication circuits. This may help to avoid
unnecessary engine removal.
Review the following:

4994257

4994104

Page 8

December, 2022

Bulletin No.: 18-NA-073

Shown are oil filter pleats with visible metal particles.
In this example, minimal amounts of metal particles are
visible on oil filter pleats and should not pose a
concern.
If excessive amounts of metal particles are observed,
or if there is evidence of damaged oil filter pleats, then
unfiltered oil with bearing debris may have been
pumped into the oil lubrication galleries throughout the
engine. This will require further inspection to confirm
the degree of contamination and appropriate repair
direction. Refer to Service Bulletin #19-NA-256 for
HFV6 Gen 1 and Gen 2.

4994408

Version Information
Version

8

Modified

Released March 07, 2018
Revised February 07, 2020 – Added the 2020 Model Year, updated the Involved Region
or Country section, updated some PI references and changed the bulletin reference in the
Oil Filter – Inspect for Excessive Debris section.
Revised January 22, 2021 – Added the 2021 Model Year and updated Involved Region or
Country section.
Revised April 13, 2021 – Added a graphic under Cylinder Bore section, added Cylinder
Out-of-Round section and updated the PI reference under Information and Cylinder Bore
sections.
Revised July 27, 2021 – Removed references to PIP5163E and changed the word
toothpick to pick under Cylinder Bore section.
Revised August 06, 2021 – Removed Australia/New Zealand from the Involved Region or
Country section.
Revised January 18, 2022 – Added the 2022 Model Year.
Revised December 14, 2022 – Added the 2023 Model Year and updated the Involved
Region or Country section.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.

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