23-NA-122

Bulletin No.:
Service Bulletin
Date:
23-NA-122
December, 2023
TECHNICAL
Subject:
Brand:
Buick
Chevrolet
Engine Oil Leak
Model:
Model Year:
from
Encore GX
2020
Envista
2024
Trax
2024
Trailblazer
(VIN M)
2021
Copyright 2023 General Motors LLC. All Rights Reserved.
VIN:
to
from
to
2024
—
—
Engine:
Transmission:
1.2L Turbo
(RPO LIH)
—
Page 2
December, 2023
Bulletin No.: 23-NA-122
Involved Region or Country
North America
Condition
Some customers may comment on oil leak between the engine front cover and
turbocharger heat shield.
6373157
Cause
This condition may be caused by porosity from the engine block bolt holes.
Important: Do Not replace the engine for this condition.
6373160
– Oil leaking was found to be coming from porosity between the cylinder head bolt hole
and the engine mount boss, bolt hole.
Correction
Remove the cylinder head bolt to apply Loctite© 565 to a new bolt. Refer to the Service
Procedure.
Bulletin No.: 23-NA-122
December, 2023
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
3. Apply 565 Loctite© to a new cylinder head bolt as
indicated in the graphic above.
4. Install the bolt into the cylinder head and torque to
14.5 Y (10.7 lb ft). Refer to Fastener
Specifications in the Service Manual.
5. Install the exhaust camshaft sprocket. Refer to
Camshaft Exhaust Sprocket Replacement in the
Service Manual.
Parts Information
Causal
Part
Description
Part
Number
Qty
N/A
N/A
BOLT, CYL HD
11548171
1
CLAMP,
EXH PIPE
55513359
1
N/A
GASKET,
CTLTC CONV
12641115
1
N/A
CLAMP, PCV
VAC HOSE
24585201
2
N/A
PIPE, TURBO
COOL FEED
55487866
1
N/A
GASKET, TURBO
OIL RTN PIPE
55514397
2
N/A
SEAL, TURBO
OIL RTN PIPE
55487539
1
N/A
WASHER,
TURBO OIL
FEED PIPE
55497445
1
N/A
NUT, EXH SYS
INTER
11612078
4
N/A
GASKET, CM/
SHF CVR
55487546
1
N/A
BOLT, CR/
SHF BALR
25194208
1
N/A
COVER, TMG
BELT LWR
55487381
1
N/A
BOLT, CM/
SHF SPKT
55487704
2
N/A
HOSE, PCV VAC
55513554
1
N/A
GASKET, EXH
SYS FRT
13499082
1
N/A
PIPE, TURBO
COOL FEED
55509610
1
N/A
OIL, ENGINE
N/A
COOLANT
Refer
to EPC
As Required
N/A
LOCTITE
565
1
6373158
Note: Camshaft removed for clarity.
1. Remove the exhaust camshaft sprocket and
position aside. Refer to Camshaft Exhaust
Sprocket Replacement in the Service Manual.
2. Remove the cylinder head bolt.
6373161
Important: Do Not apply Loctite© to the end of the
bolt. Damage to the engine block may occur.
Page 3
Page 4
December, 2023
Bulletin No.: 23-NA-122
Warranty Information
For vehicles repaired under the Powertrain coverage,
use the following labor operation. Reference the
Applicable Warranties section of Investigate Vehicle
History (IVH) for coverage information.
Labor
Operation
4089088*
Description
Labor Time
Add Loctite© to Cylinder
Head Bolt
3.6 hrs
*This is a unique Labor Operation for bulletin use only.
Version
1
Modified
Released December 18, 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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