LOSS OF POWER/DELAYED ENGAGE THM325-4L DIAG.AND REPAIR

DELAYED ENGAGEMENT AND/OR LOSS OF POWER - THM 325-4L TRANSMISSION

This bulletin provides service information for 1982 and 1983 Eldorados and Sevilles equipped with THM 325-4L transmissions exhibiting either delayed engagement when moving shift selector from Park to Reverse or an apparent loss of engine power resulting from improper lo and reverse clutch operation.

I. DELAYED ENGAGEMENT FROM PARK TO REVERSE AFTER A LO AND REVERSE CLUTCH OVERHAUL

Delayed engagement (cold or hot) when moving the transmission shift selector from Park to Reverse after a complete service overhaul of a THM 325-4L transmission can be caused by an insufficient number of flat steel plates installed in the lo and reverse clutch assembly. The lo and reverse clutch assembly should have one waved steel, seven flat steel and six composition faced plates installed in it, as illustrated in Figure 325-4L-100 on Page 325-4L-32 of the 1983 Service Information Manual.

To assure proper lo and reverse clutch plate assembly, step #2 of the lo and reverse clutch assembly procedure on Page 325-4L-31 of the 1983 Service Information Manual should be changed to:

2. Install the waved steel plate on top of the last flat steel plate (Figure 101).

II. APPARENT LOSS OF ENGINE POWER

An apparent loss of engine power or transmission operation in two gears at one time on any THM 325-4L transmission can be caused by an incorrect application of the lo and reverse clutch assembly. This incorrect apply of the lo and reverse clutch can be caused by a missing locator pin securing the Lo-1st Detent Valve Bushing in the control valve assembly (refer to Item A in Figure 1 on the reverse side of this bulletin).

A missing pin will permit the bushing to rotate in its control valve/bore and apply the lo and reverse clutch through the use of "detent" oil. (Detent oil is available whenever the throttle angle is at or above approximately 60 DEG of travel.)

To correct this condition, reroute the valve body, orient the bushing correctly in its bore and install a locator pin (P/N 8628400). (The locator slot in the Lo-1st Detent Valve Bushing is not illustrated in the figure due to its orientation.)

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.