21-NA-238

Bulletin No.:
Service Bulletin
21-NA-238
Date:
February, 2024
TECHNICAL
Subject:
Transmission Fluid Leak Near Bellhousing Area
Brand:
Model:
Chevrolet
Silverado 2500HD/
3500HD
GMC
Sierra 2500HD/
3500HD
Model Year:
from
to
2020
2024
VIN:
from
to
Engine:
Transmission:
L5P, L8T
MGM, MGU, MKM
Involved Region or Country
North America, Australia, New Zealand.
Condition
Some customers may comment that a transmission fluid leak is coming from the
bellhousing inspection cover.
Cause
This condition may be caused by the Automatic Transmission Case Front Cover Seal
may be rolled or damaged.
Correction
If the leak has been verified to be coming from the front cover seal, replace the Automatic
Transmission Case Front Cover Seal and the Torque Converter Fluid Seal.
Parts Information
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.
Causal
Part
Description
Part
Number
Qty
X
SEAL, T/C FLUID
24293986
1
X
SEAL AUTO
TRANS FRT
CASE COVER
24277112
1
N/A
SEAL, TRANS
FLUID CLR PIPE
85630659
1
N/A
PLATE, CLU
PRESS
24052451
1
N/A
BOLT/SCREW-A/
TRNS CASE
FRT CVR
11604747
15
N/A
BOLT, TRNS MNT
11548787
2
N/A
NUT, TRNS MNT
11548414
3
N/A
MOUNT, TRANS
85573625
1
N/A
SEAL, OUTPUT
SEAL
SQUARE CUT
24286193
1
N/A
FLUID, AUTO
TRNS ULV
19352619
(U.S.)
19352620
(Canada)
15
Service Procedure
Refer to Automatic Transmission Case Front Cover
Removal in SI and Torque Converter Fluid Seal
Replacement in SI.
Note: Case Front Cover Bolt Specification 10.5 NM (88
In LBs)
Copyright 2024 General Motors LLC. All Rights Reserved.
Page 2
February, 2024
Bulletin No.: 21-NA-238
Labor Operation
Description
Labor Time
8466580
Automatic Transmission Case Front Cover Seal Replacement
Use the Published Labor
Operations Time
Warranty Information
For vehicles repaired under warranty, use:
Version
6
Modified
Released November 09, 2021
Revised February 17, 2022 - Add 2022 to Model Year.
Revised January 19, 2023 - Added Plate, Clutch Pressure and SEAL, TRANS FLUID
CLR PIPE to Parts Information section.
Revised January 03, 2024 - Added 2023 to 2024 Model Years, Added RPO MKM and
Added 11604747 to Parts Information section.
Revised January 22, 2024 - Added L8T to Engine section, Note to Service Procedure
section and Added New Pipe Seal and Plate Part Numbers.
Revised February 20, 2024 - Added Transmission Mount to Parts Information 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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