THM 325 DELAYED ENGAGEMENT REVERSE/ DRIVE

DELAYED TRANSMISSION ENGAGEMENT - 1980 AND 1981 SEVILLE AND ELDORADO 00

To diagnose a THM 325 transmission (1980 and 1981 Seville and Eldorado) for delayed engagement from park or neutral to any drive gear after start-up, follow this procedure:

Make a cold oil pressure check. If oil pressure readings are normal, follow the service manual trouble diagnosis section. If a zero oil pressure reading is detected on a temporary basis prior to engagement of reverse and/or drive, check the following:

a) Check the pump body to gear face clearance: should be .030/.069mm (.0012/.0027 inch). If necessary, replace the gear and pump body assembly.

b) If the transmission contains an oil pump spacer plate, check it for damage and replace it, if necessary.

c) If no other cause can be found, check the casting number on the case cover. If the casting number is 8632010 or 8632695, the part is a first design case cover and the condition may be corrected by installing the parts contained in service package number 8632987 (soon to be available) which will include a second design case cover (identified by casting number 8632810) and the parts necessary to install this case cover.

The the second design case cover is installed on any THM 325 transmission which currently contains an oil pump spacer plate, refer to Serviceman Bulletin 80-73 (Group 7, No. 12) before installation.

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.