23-NA-170

Bulletin No.:
Service Bulletin
Date:
23-NA-170
March, 2024
INFORMATION
Subject:
Diagnostic Tips for Seized or Hard to Rotate Engine, Internal Engine or Transmission
Noise Thump, Knock, Rattle and/or Starter Fuse Blown
This bulletin replaces PIP5900. Please discard PIP5900.
Brand:
Model:
CT5
Cadillac
Escalade
Model Year:
from
to
2022
2021
2024
6.2L (L87)
2023
6.2L (LT4)
2019
6.2L (LT1, (LT4)
Corvette
2019
Express
2021
Silverado 1500
(New Model)
2019
2019
Silverado 1500
2020
2021
Silverado 1500 New
(RPO J22, VIN Digit 5 =
A/D)
2022
2022
Silverado 1500
2023
Silverado
2500HD/3500HD
2020
Suburban
2021
Tahoe
2021
Savana
2021
2024
Sierra 1500
(New Model)
2019
2019
Sierra 1500
2020
2021
2022
2022
Sierra 1500 New (RPO
J22, VIN Digit 5 = H/U)
Sierra 1500
2023
Sierra
2500HD/3500HD
2020
Yukon
2021
Copyright 2024 General Motors LLC. All Rights Reserved.
Transmission:
to
Camaro
Sierra 1500 Limited (RPO
J21, VIN Digit 5 = 8/9)
GMC
from
Engine:
6.2L (LT4)
2024
6.2L (LT1,
LT4, LT2)
6.6L (L8T)
Silverado 1500 LTD (RPO
J21, VIN Digit 5 = W/Y)
Chevrolet
VIN:
4.3L (LV3)
5.3L (L82)
5.3L (L84)
6.2L (L87)
6.6L (L8T)
2024
5.3L (L84)
6.2L (L87)
5.3L (L84)
6.2L (L87)
2024
6.6L (L8T)
4.3L (LV3)
5.3L (L82)
5.3L (L84)
6.2L (L87)
6.6L (L8T)
5.3L (L84)
6.2L (L87)
M1L
M1M
M5U
N8X
MF6
MGL
MHO
MHS
MHT
MHU
MHW
MHX
MI2
MI4
MLM
MQB
MQD
MQE
MTH
MYC
MYD
Page 2
March, 2024
Bulletin No.: 23-NA-170
Involved Region or Country
North America, Europe, Kazakhstan, Uzbekistan, Russia, Middle East, Iraq, Israel,
Palestine, Argentina (Mercosur), Brazil (Mercosur), Bolivia (West), Chile (West),
Colombia (West), Ecuador (West), Paraguay (West), Peru (West), Uruguay (West),
Venezuela (West), Other Central America, Japan, Cadillac Korea (South Korea), GM
Korea Company, China - SGM, Taiwan , Thailand (ASEAN), Singapore, Philippines,
Australia/New Zealand, Caribbean, Egypt, Other Africa, South Africa
Condition
Some 4.3L, 5.3L, or 6.2L engines may not crank due to being seized with possible starter
fuse being open.
Various engine noises such as but not limited to:
• Thumping (which may be perceived as upper engine noise or possibly from the
transmission as shown in the video above.)
• Growling
• Knocking
• Rattling
Engine may also exhibit a condition of stalling or being hard to rotate once at operating
temperature. Engine could also be locked up and unable to restart. However, upon
engine cooling down to ambient temperature the engine may refire and run normally. This
can be a sign of an early bearing failure.
Cause
This condition may be caused by a crankshaft bearing failure and/or possible damaged
thrust bearing.
Bearings Diagnosis:
If any of the above issues are present and the condition has been identified as an internal
engine concern, the following may be helpful:
Note: If the engine has not had its first oil change it is possible to see some light glitter in
the oil. This could be build debris from the manufacturing process that is flushed out after
the engine has been in operation. Further inspection in this case will be necessary.
– Inspect the engine oil and filter for excessive metal debris, specifically bearing
material.
⇒ If bearing debris has been identified, then it will be necessary to remove the
engine oil pan for further inspection of the crankshaft rod and main bearings.
If it has been found there is damage to the crankshaft bearings, please follow the latest
versions of Technical Service Bulletins 22-NA-074 and 18-NA-073 for further repair
direction.
Information
Diagnostic Aids: Stationary Vehicle:
• At a warm idle, increase the engine RPM to 1500 - 1800, and release to see if the
noise intensity increases and decreases
• The use of a stethoscope or Pico scope may show the noise is in the bellhousing or
rear of the transmission.
• Remove the engine oil filter and inspect for metallic and bearing material. Pouring the
engine oil through a white shop towel may be helpful. If material is found perform a
crankshaft end play measurement following published Service Information. Replace or
repair the engine as necessary.
• DO NOT back the torque converter off from the engine and run the engine in an effort
to isolate the noise to the engine or transmission. Many evaluations indicate the noise
is eliminated when the transmission disconnected however replacing the transmission
does not resolve the noise condition. Doing so may also cause engine and or
transmission damage.
• If excessive crank end play is not found the engine accessory drive belt should be
removed and the engine ran again to see if the noise eliminated. If the noise is
eliminated check the accessory drive belt driven components for possible issues.
If it has been found there is damage to the crankshaft bearings, please follow the latest
versions of Technical Service Bulletins 22-NA-074 and 18-NA-073 for further repair
direction.
Bulletin No.: 23-NA-170
March, 2024
Page 3
Starter Concerns:
• If you find it necessary to replace the engine assembly, upon completion of the engine
replacement, ensure that the engine starts and runs as designed and there are no
other concerns.
– If the starter fuse is or was blown replace the starter fuse and ensure the vehicle
starts up and operates as designed
• If you noticed that the starter fuse was blown it will be necessary to replace the starter
fuse once new engine is installed. Do not replace the starter assembly. After fuse
replacement, if you find that there may be a starter concern refer to diagnostic
information in service information for further details.
Important: Service agents must comply with all
International, Federal, State, Provincial, and/or
Local laws applicable to the activities it performs
under this bulletin, including but not limited to
handling, deploying, preparing, classifying,
packaging, marking, labeling, and shipping
dangerous goods. In the event of a conflict between
the procedures set forth in this bulletin and the
laws that apply to your dealership, you must follow
those applicable laws.
Version
4
Modified
Released September 19, 2023
Revised September 22, 2023 - Revise Model section and added Additional Countries to
Involved Region or Country section.
Revised January 16, 2024 - Added 2024 Model Year to Applicable Models.
Revised March 11, 2024 - Added Transmission RPO, Update Correction section to add a
video and additional Information, Update Information section to add a Note under Bearing
Diagnosis section, Added Diagnostic Aids: Stationary Vehicle 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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