23-NA-017

Service Bulletin
Bulletin No.:
23-NA-017
Date:
April, 2023
TECHNICAL
Subject:
High Pitched Squealing, Moan or Whistling Noise at Idle
Brand:
Model:
Chevrolet
Silverado
2500HD/3500HD
GMC
Sierra
2500HD/3500HD
Model Year:
from
to
2022
2023
VIN:
from
to
Engine:
Transmission:
L8T
Involved Region or Country
North America
Condition
Some customers may comment that a high pitch squeal, moan or a whistling noise can
be heard at idle
Some technicians may comment that the noise can be heard at the rear main seal of the
engine and may continue for a few seconds after the engine is shut off.
Cause
6270638
This condition may be caused by excessive crankcase vacuum from a restriction on the
PCV of the air cleaner outlet duct.
Correction
Copyright 2023 General Motors LLC. All Rights Reserved.
If the noise has been validated, remove the oil cap or oil level indicator to verify that the
noise has been eliminated.
If the noise has been eliminated, replace the air cleaner outlet duct.
Page 2
April, 2023
Bulletin No.: 23-NA-017
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.
Service Procedure
Refer to Air Cleaner Outlet Duct Replacement in the
Service Manual.
Parts Information
Causal
Part
Description
Part
Number
Qty
X
DUCT ASM-A/
CL OTLT
84841228
1
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
4020690
Description
Labor Time
Air Cleaner Outlet Duct Replacement
Use the Published Labor
Operations Time
Version
1
Modified
Released March 31, 2023
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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