NHTSA ID Number: 11006707
Manufacturer Communication Number: 18-NA-098
TSB/Document Date: 2024-08-30
Summary
This informational bulletin provides information for the technicians on where to look on the Duramax engine for coolant leaks.
Bulletin No.: 18-NA-098
Service Bulletin
Date: August, 2024
INFORMATION
Subject:
Brand:
Diagnostic Tip for Coolant Leak, Coolant Consumption and/or Low
Coolant Message Being Displayed On the Driver Information Center (DIC)
Model:
Model Year:
from
to
Silverado
2017
2018
Silverado 2500/3500
2019
2025
Silverado 4500HD,
5500HD and 6500HD
2019
2025
Sierra
2017
2018
Sierra 2500/3500
2019
2025
VIN:
from
Engine:
to
Equipped with 6.6L
Diesel Engine (RPO
L5P, L5D)
Involved Region or Country
North America, Middle East, Australia, New Zealand.
Condition
Some customers may comment on a coolant leak, coolant consumption and/or low coolant message being displayed on the driver information center (DIC).
Correction
Use the illustrations below, that show the areas in blue, to help identify where to look for
possible coolant leak paths for the Duramax engine.
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.
Copyright 2024 General Motors. All Rights Reserved.
Page 2
August, 2024
Bulletin No.: 18-NA-098
5027608
1. Plugs in Cylinder Head (PLUG, CYL HD CORE
HOLE) (Qty 8)
3. Cup Plugs in Block (PLUG, ENG BLK COOL DRN
HOLE (OD=40MM) (Qty 5)
2. Block Heater (HEATER, ENG COOL)
5027641
1. Coolant Hose and Clamp
2. Thermostat Housing (SEAL, ENG COOL THERM
(O RING)
3. O-Ring for Bypass Pipe (SEAL, THERM BYPASS
PIPE (O RING))
4. Flange with Gasket for Bypass Pipe (GASKET,
THERM BYPASS PIPE)
5. O-Ring Seal (Front Cover to Water Pump) (SEAL,
W/PMP CVR)
6. Seal-Water Pump to Pipe (GASKET, W/PMP OTLT
PIPE)
7. Coolant Hose and Clamp
8. Cup Plug on Block (PLUG, ENG BLK COOL DRN
HOLE)
Bulletin No.: 18-NA-098
August, 2024
Page 3
5028324
1. O-Ring (Water Pipe to Oil Cooler) (SEAL, W/PMP
OTLT PORT)
3. Seal in the Oil Coolet (GASKET, ENG OIL CLR)
2. Either end of the Oil Cooler Adapter (Elbow)
(GASKET, ENG OIL CLR ADAP)
Note: Ghost view of the Oil Cooler to reveal O-ring and
cover gasket and 2 adapter gaskets (Oil Filter not
shown).
1. Cup Plugs (Qty 2)(One per side in rear of Cylinder
Head) (PLUG, CYL HD CORE HOLE)
7. Cover on Flywheel Housing (GASKET, FLYWHL
HSG CVR)
5028590
2. Gaskets under Flange, 1 location on EGR Bypass
Valve (Serviced with VALVE, EGR VLV CLR
BYPASS)
3. Hose Clamps, 5 locations
4. Turbo Coolant Feed Pipe (GASKET, TURBO
COOL FEED & RTN PIPE)
5. Gaskets under Flange, 2 locations on EGR Valve
(Service with VALVE, EGR)
6. Cup Plug in Bypass Valve (Service with VALVE,
EGR)
Page 4
August, 2024
Bulletin No.: 18-NA-098
Note: A leak on the top of the engine will trail down the
back of the engine and appear as a rear cover leak.
1. Hose Clamps on the EGR Coolant Return Hose
(Qty 2)
2. O-Ring for EGR Coolant Return Pipe (SEAL, EGR
COOL FEED PIPE) (Qty 2)
3. Gaskets under Flanges for EGR Coolant Feed and
Return Pipes (SEAL, EGR COOL FEED PIPE)
(Qty 2)
5028593
1. Gasket for Turbo coolant pipes (GASKET, TURBO
COOL FEED & RTN PIPE) (Qty 2)
2. Ghost view of Upper Intake Manifold and ERG
Coolant Pipe. Inlet Adapter removed to reveal
EGR Coolant Return Pipe.
3. Hose Clamps for Turbo Coolant Pipes and DEF
Coolant Pipe (Qty6)
5028676
1. Gaskets between Cylinder, Heads and Water
Crossover Housing (GASKET, ENG COOL
THERM HSG) (Qty 2)
2. Head Gaskets (GASKET, CYL HD)
5028604
Bulletin No.: 18-NA-098
August, 2024
Page 5
Version
8
Modified
Released April 05, 2018
Revised July 25, 2018 - Added the 2019 to Model Year.
Revised June 24, 2019 – Added the 2020 Model Year.
Revised November 06, 2020 — Added 2021 Model Year and Silverado 4500HD, 5500HD
and 6500HD
Revised January 11, 2022 - Added 2022 to Model Year.
Revised September 09, 2022 - Added 2023 to Model Year.
Revised March 14, 2023 - Added 2024 Model Year to Silverado 2500/3500.
Revised August 09, 2024 - Added 2025 to Model Year.
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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TSB/Document ID: 18-NA-098
Replacement Service Bulletin Number:
MFR Communication Date: 2024-08-09
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: ENGINE
MFR Component System:
MFR Component Subsystem:
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