6.6L Duramax Possible Oil Leak Path Information – 2017-2023 Chevrolet Silverado & GMC Sierra

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Copyright 2022 General Motors LLC. All Rights Reserved. Service Bulletin Bulletin No.: 18-NA-150 Date: September, 2022 INFORMATION Subject: 6.6L Duramax Possible Oil Leak Path Information Brand: Model: Model Year: VIN: Engine: Transmission: from to from to Chevrolet Silverado 2017 2018 L5P, L5D Silverado 2500/3500 2019 2023 Silverado 4500HD, 5500HD, 6500HD 2019 2023 GMC Sierra 2017 2018 Sierra 2500/3500 2019 2023 Involved Region or Country North America, Middle East, Israel, South America and Thailand. Additional Options (RPOs) Equipped with 6.6L Diesel Engine (RPO L5P or L5D) 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. This document is to help identify where to look for an oil leak on the 6.6 Duramax engine. Note: Please keep in mind that a leak on the top of the engine will trail down the back side of the engine and appear as a rear cover leak. Please use the illustrations below as a guide of where to look for a potential oil leak. These Illustrations are of a L5P engine; the L5D would be similar. Page 2 September, 2022 Bulletin No.: 18-NA-150 Possible Oil Leak Paths 5053868 Legend (1) GASKET, VLV RKR ARM CVR (Rocker Cover Gasket) (2) GASKET, CYL HD (Head Gasket) (3) SENSOR, ENG OIL PRESS (Oil Pressure Sensor) (4) PLUG, ENG BLK OIL GAL (Plugs in Block Qty 4) (5) SEAL, OIL LVL IND TUBE (O-Ring on Oil Indicator Tube) (6) SEAL, ENG OIL LVL IND SW (Oil Level Sensor) (7) SEAL, OIL PAN DRN PLUG (Oil Drain Plug) 5053869 Plugs and Gaskets in Oil Cooler and Filter Bulletin No.: 18-NA-150 September, 2022 Page 3 5053871 Ghost view of the Oil Cooler Cover to reveal 2 O-rings (SEAL, ENG OIL CLR). 5053872 Legend (1) GASKET, TURBO OIL FEED PIPE (Turbo Oil Feed Pipe into Block, Turbo Pipe removed for picture only) (2) PLUG, ENG BLK OIL GAL (Section cut through Flywheel housing to show 2 plugs on the back of the engine block ) 5053874 Legend (1) GASKET, TURBO OIL RTN PIPE (Turbo Oil Drain Pipe Gaskets (Quantity 3)) Page 4 September, 2022 Bulletin No.: 18-NA-150 5053875 Legend (1) SEAL, OIL FIL CAP (Oil Separator Gaskets) (2) GASKET, TURBO OIL FEED PIPE (Turbocharger Oil Gasket (2) ) 5053878 Legend (1) PLUG, ENG BLK OIL GAL (Oil Gallery Plug) (2) RTV (Oil Pan Seals) (3) PLUG, CYL HD OIL GAL (Upper Oil Pan Plug) Bulletin No.: 18-NA-150 September, 2022 Page 5 5053879 Legend (1) RTV (Front Cover Seal) (2) SEAL, CR/SHF FRT OIL (Front Bearing Seal) 5053880 Note: (Flywheel Housing has been removed for clarity of picture) Legend (1) RTV (Flywheel Housing Seal) (2) SEAL, CR/SHF RR OIL (Rear Bearing Seal) Page 6 September, 2022 Bulletin No.: 18-NA-150 Version 6 Modified Released May 04, 2018 Revised July 25, 2018 – Added the 2019 Model Year. Revised June 24, 2019 – Added 2500/3500 to Models and 2020 to Model Year section. Revised October 19, 2020 – Added 2021 Model Years to 2500/3500 models and added 2019–2021 Silverado 4500, 5500 and 6500 HD Models and added RPO L5D. Revised January 07, 2022 – Added 2022 to Model Year. Revised September 09, 2022 – Added 2023 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. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

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