BURNT INTERMEDIATE BAND DIAGNOSIS-125 TRANSMISSION

SOME 1982 VEHICLES EQUIPPED WITH A THM 125C TRANSAXLE MAY EXPERIENCE A CONDITION OF A SLIPPING 2-3 UPSHIFT AND/OR NO 3RD GEAR OPERATION. THIS CONDITION IS EVIDENCED BY BURNT INTERMEDIATE BAND AND DIRECT CLUTCH ASSEMBLIES RESULTING FROM THE INTERMEDIATE BAND DRAGGING WHILE THE DIRECT CLUTCH IS APPLIED. THIS SIMULTANEOUS INTERMEDIATE BAND AND DIRECT CLUTCH APPLICATION CAN BE CAUSED BY THE THIRD ACCUMULATOR CHECK VALVE NOT SEATING PROPERLY. TO CORRECT THE POSSIBLE RECURRENCE OF THIS CONDITION, A SERVICE PACKAGE (P/N 8643964) WHICH CONTAINS A NEW DESIGN DUAL LAND THIRD ACCUMULATOR CHECK VALVE AND A CONICAL SPRING (REFER TO FIGURE 1 ON REVERSE SIDE OF BULLETIN) MUST BE INSTALLED. TO INSTALL THE VALVE AND SPRING WITH THE TRANSAXLE ON THE BENCH, PROCEED AS FOLLOWS: 1.REMOVE THE INTERMEDIATE SERVO COVER AND GASKET. 2.REMOVE THE THIRD ACCUMULATOR CHECK VALVE AND SPRING. 3.INSPECT THE VALVE SEAT IN THE THIRD ACCUMULATOR VALVE BORE, IN THE TRANSAXLE CASE FOR WEAR OR DAMAGE TO THE SEAT (REFER TO FIGURE 1). 4.PLUG THE FEED AND RELEASE HOLES IN THE BORE USING PETROLATUM (REFER TO FIGURE 1). 5.REPLACE THE ORIGINAL THIRD ACCUMULATOR CHECK VALVE WITH THE NEW DESIGN DUAL LAND CHECK VALVE (DO NOT INSTALL THE CONICAL SPRING AT THIS TIME). CENTER THE VALVE TO SEAT IT PROPERLY. 6.LEAK TEST THE VALVE SEAT BY POURING SOLVENT INTO THE ACCUMULATOR CHECK VALVE BORE. CHECK FOR A LEAK ON THE INSIDE OF THE CASE. (A SMALL AMOUNT OF SEEPAGE IS ACCEPTABLE). 7.IF THE VALVE LEAKS, TAP THE VALVE USING A BRASS DRIFT AND A RUBBER MALLET TO TRY TO RESEAT THE VALVE. 8.LEAK TEST THE VALVE SEAT AGAIN. 9.IF THE VALVE CONTINUES TO LEAK AFTER REPEATED ATTEMPTS TO SEAT IT PROPERLY, IT WILL BE NECESSARY TO REPLACE THE TRANSAXLE CASE (P/N 8631974). 10.IF THE VALVE DOESN'T LEAK, REMOVE THE CHECK VALVE AND INSTALL THE NEW CONICAL VALVE SPRING ONTO THE VALVE (SMALL END FIRST AS SHOWN IN FIGURE 1). INSTALL THE VALVE INTO THE CASE BORE. 11.INSTALL THE INTERMEDIATE SERVO COVER WITH A NEW GASKET (P/N 8631698).

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those 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 a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.