A/T - THM 440-T4 Pan Bolt Leaks
90chevy21Number: 91-19-7A
Section: 7A
Date: May 1990
Corp. Bulletin No.: 077120
Subject: TRANSAXLE BOTTOM PAN BOLT LEAKS
Model and Year: 1984-91 A CAR AND 1990-91 W CAR WITH 4T60 (THM440-T4) F-7 AUTOMATIC TRANSMISSION
BULLETIN COVERS:
Whenever the bottom pan has been removed on any HYDRA-MATIC 4T60 (THM 440-T4) or THM F-7 transaxle, it may be necessary to use LOCTITE 242 (R) (or equivalent) to reduce the potential for fluid leaks on any blind (not through) bolt holes for bottom pan bolts. The fluid leak could be caused by porosity.
SERVICE PROCEDURE:
If the transaxle has a leak from a bottom pan bolt(s), clean the bolt(s) and bolt hole(s) in the transaxle case with a suitable solvent to insure that it is free of dirt and transmission fluid. Apply Loctite 242 (R) (or equivalent) to the bolt per the sealant manufacturer's instructions and allow the compound to cure according to the sealant manufacturer's recommendations.
IMPORTANT:
The fluid leak could also be caused by a cut or damaged 1-2 servo seal or other damaged seals or gaskets in the leak area. If necessary, use one of the fluid leak diagnosis methods like the powder or the black light and dye methods listed in section 7A of the Service Manual. Correct the leak as necessary.
SERVICE PARTS INFORMATION:
Part Number Description
12345382 Loctite 242 (R) (or equivalent)
Parts are currently available from GMSPO.
NOTICE: Loctite 242 (R) is a removal threadlocker. Do not use stronger threadlockers like Loctite 290 (R) or the Loctite threadlocking kit (R). The aluminum threads may come out with the bolt the next time the bolt is taken out.