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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