Chevette L4-111 1.8L DSL (1983)
fitting is blocked off, the second clutch check ball vibrates back and forth against the spacer plate causing the distortion.
To service a THM 180/180C transmission for a slipping or no upshift condition, inspect and replace as necessary, the second clutch plates, third clutch
plates, the valve body spacer plate and gaskets. Check the vacuum modulator, using J 24466 Modulator Checking Tool; and clean the vacuum pipe
fitting assembly.
To clean the vacuum pipe fitting assembly:
remove the fitting from the intake manifold and clean the orifice using a 7/64" drill bit (turning
drill bit by hand). Carburetor cleaner may be used to loosen carbon deposits if needed.
NOTICE:
To prevent a vacuum leak when reinstalling the fitting, use pipe sealant, service part number 1052080, around the threads.
Any time transmission service is performed on a Chevette equipped with a THM 180/180C transmission, the vacuum pipe fitting should be inspected and
cleaned.
