A/T - Slipping or No Upshift/Burned Second Clutch
Number 87-7-19 Date 4/87Subject: SLIPPING OR NO UPSHIFT - BURNED SECOND CLUTCH
1981-87 T1000 MODELS EQUIPPED WITH THM 180/180C TRANSMISSIONS (MD3/MD2)
Figure 1 - THM 180/180C Transmission Identification Information:
Figure 2:
TRANSMISSION MODELS:
ND, NS, VN, ST, VQ, TN, TP, PR, UR
BULLETIN COVERS:
A 1981 through 1987 THM 180/180C transmission (refer to Figure 1) may exhibit a slipping or no upshift condition due to a burned second clutch. The burned second clutch may be due to distortion of the valve body spacer plate which results in loss of second clutch apply pressure. The valve body spacer plate may become distorted when the vacuum pipe fitting (refer to Figure 2) becomes blocked by carbon at the engine intake manifold. As the fitting is blocked off, the second clutch check ball vibrates back and forth against the spacer plate causing the distortion..
SERVICE ACTION:
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 7/16" 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.
SERVICE NOTE:
Any time transmission service is performed on a T1000 model equipped with a THM 180/180C transmission, the vacuum pipe fitting assembly should be inspected and cleaned.
SERVICE MANUAL REFERENCE:
Refer to Second and/or Third Clutch Assembly section of the THM 180C Unit Repair Service Manual.