22-NA-173
Service Bulletin Details
Public Details for: 22-NA-173
This service bulletin provides information help guide technicians to known areas of possible transmission fluid leaks.
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2023 CHEVROLET CORVETTE |
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Bulletin No.: Service Bulletin Date: 22-NA-173 October, 2023 INFORMATION Subject: Information on Transmission Fluid Leak Brand: Model: Chevrolet Corvette Model Year: VIN: from to from to 2020 2024 — — Engine: Transmission: All All Involved Region or Country North America, Europe, Middle East, Australia/New Zealand Condition Some customers may comment that transmission fluid can be seen under the vehicle. Information The following photos are only for informational purposes and to help guide technicians to known areas of possible leaks. Testing in the photos used fluorescent dye to aid in better photography. These transmissions were scrapped after dye was added. At no time should a technician in the field add dye to the M1L transmission. Technicians should only follow the trace powder diagnosis procedure recommended in Fluid Leak Diagnosis in the Service Manual. 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. Examples of Transmission Leak Areas of Concern When performing a leak test always be sure to clean the transmission thoroughly prior to powder testing. Make an attempt to protect the transmission labels from any type of solvent that may be used. Solvents can erase the print on the labels and make the transmission difficult to identify. A great opportunity to recreate the leak after powder application is to perform the Hydraulic System Leak Test in service information document 5659563 multiple times until a leak is visible. Because of the elevated RPMs in this test and the vehicle being stationary, always monitor engine temperature. If the coolant temperature is excessive and fans continue to run it may be necessary to allow the vehicle to cool before continuing testing. Copyright 2023 General Motors LLC. All Rights Reserved. Page 2 October, 2023 Bulletin No.: 22-NA-173 6142752 A leak between sealing plate and Bell Housing. 6142966 Leaks at the gasket area between the clutch and differential cover and the main case. There is a gasket in this area. This video above shows transmission case porosity, issue during testing. Bulletin No.: 22-NA-173 October, 2023 Page 3 6142841 This is an area that is often mis-diagnosed as a transmission cooler issue. It was found that in most cases, leaks in this area are caused by transmission case porosity under the transmission cooler. Proper diagnosis in this area would be to inspect the cooler for any signs of physical damage. If no damage is found, carefully remove the cooler, and inspect the two (14) O-rings for damage and proper sealing. The dye photo shows a puddle of oil just under the cooler sealing area in the pocket, the fluid is being pushed through the case due to material porosity. This concern will require transmission assembly replacement. 6142814 A small crack in the clutch cover area (1) of the input shaft seal can be mis-diagnosed as an input shaft seal leak (3). Additional cases have been verified at the input shaft end plug/seal (2), was damaged during transmission to engine mating. Page 4 October, 2023 Bulletin No.: 22-NA-173 6142818 Porosity concerns with the differential cover. This area needs to be carefully powder tested to verify the leak is not associated with the cover seal (16) or the dog-bones and seals. Technicians have stated that they have found the cover double-gasketed when they confused the metal differential shims with what they thought were gaskets. All shims need to be re-installed to retain proper bearing load on differential. If porosity is found in the cover, the transmission will require replacement. 6142744 The auxiliary canister filter can create leaks in several areas. The most common area is cover seal (20), O-ring installation issues after filter replacement. Other areas of concern can be found at the are O-rings (12) and (17). Bulletin No.: 22-NA-173 October, 2023 Page 5 Note: Inspect the cover prior to replacement of the seal for porosity issues in the O-ring groove area. 6456550 Transmission rear cover area leak. (Tremec name plate): • If there seems to be a leak in this area, be sure to clean the area thoroughly. Residual oil can get trapped between the outer surface and the O-ring. • After powder testing, if a leak re-occurs, remove the cover, and inspect the O-ring for damage. • If no obvious damage is found with the O-ring, be sure to inspect the cover itself for porosity issues in the O-ring groove. It is critical to identify the difference between a leak and dampness. 6142979 Transmission case porosity concerns have been found in the SAV cover area of the transmission. This is often the most misdiagnosed leak on this transmission. The fluid seeps through the case and runs down between the SAV cover and case to the pan rail, and often the transmission pan, and gasket get replaced, then the SAV cover, and finally the transmission. Often these leaks will not develop by just allowing the engine to run. Usually, the vehicle will need to be lifted safely on a hoist with the wheels raised to allow the vehicle to run in gear. This action applies to most porosity leaks. Page 6 October, 2023 Bulletin No.: 22-NA-173 Version 3 Modified Released August 24, 2022 Revised June 06, 2023 – Changed Engine and Transmission RPOs to All. Revised October 16, 2023 – Added the 2024 Model Year and additional Information under Examples of Transmission Leak Areas of Concern 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. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION