23-NA-032

Bulletin No.: 23-NA-032
Service Bulletin
Date: April, 2024
INFORMATION
Subject:
Brand:
Chevrolet
GMC
Information on Servicing Diesel Engines with Ceramic Glow Plugs
Model:
Model Year:
VIN:
from
to
Cruze
2017
2019
LH7
Equinox
2018
2019
LH7
Silverado 1500
2020
2025
LM2, LZ0
Silverado 2500HD/
3500HD
2017
2025
L5P
Silverado 4500HD,
5500HD and
6500HD
2019
2022
L5D
Suburban
2021
2025
LM2
Tahoe
2021
2025
LM2
Sierra 1500
2020
2025
LM2, LZ0
Sierra 2500HD/
3500HD
2017
2025
L5D
Terrain
2018
2019
LH7
Yukon Models
2021
2025
LM2
Involved Region or Country
from
Engine:
to
Transmission:
North America
Tips for the successful replacement of ceramic Glow Plugs:
1. Measure the resistance of the new glow plug.
− An open circuit in a glow plug is an indication that the glow plug tip is broken and
should not be installed into an engine.
2. Do not install a glow plug into an engine if the glow plug has been dropped.
3. Pull on the tip of the new glow plug prior to installation. Be sure hands are clean before handling the glow plug.
4. Always use a Glow Plug Bore Reamer:
Information
− Whenever replacing a ceramic glow plug on a diesel engine, it is required to use a
glow plug hole bore cleaning tool to remove the soot built up on the inside of the
glow plug hole. The only exception to this is when servicing a glow plug on the 2.0 L
or 2.8 L diesel engine.
− As the engine runs during normal operation, soot builds up between the outside of
the glow plug and the inside of the glow plug hole. Once a glow plug is removed,
this soot that collected in the bore must be removed. If not, when installing a new
glow plug, the soot could "side load" the new glow plug and induce a premature failure.
− The recommended tools for cleaning these glow plug holes are as follows: 6.6 L
Diesel, 3.0 L Diesel, and 1.6 L Diesel all use the EN-52074 Glow Plug Bore Reamer
5. Never use any type of grease or anti seize on the new glow plug.
− The use of any type of lubricant could lead to over tightening of the glow plug.
Copyright 2024 General Motors. All Rights Reserved.
Page 2
April, 2024
Bulletin No.: 23-NA-032
6. When installing the Glow Plug, make sure that the glow plug is in line with the glow
plug hole.
− Any side load placed on the glow plug could lead to a crack in the ceramic leading
to premature failure.
7. Do not overtighten the glow plug.
− An overtightened glow plug could initiate a crack in the ceramic leading to premature failure.
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
2
Modified
Released March 06, 2023
Revised April 29, 2024 - Added 2024 and 2025 to Applicable Vehicles and a Procedure to
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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