HYDRULIC NOISE IN PARK/NEUT. PRESSURE REGULATOR VALVE

HYDRAULIC NOISE IN PARK AND/OR NEUTRAL - THM 325-4L

1982 and 1983 Eldorados and Sevilles equipped with THM 325-4L transmissions may experience a hydraulic buzzing sound in the park and/or neutral shift selector positions. This condition may be caused by an orifice cup plug missing from the pressure regulator valve.

To correct this condition with the transmission in the car, proceed as follows:

1. Remove the pressure regulator valve from the transmission by using Step Nos. 2, 3, 7 and 8 under the heading "EXTERNAL PARTS - Removal" on pages 325-4L-9 and 11 of the 1983 Cadillac Service Information Manual.

2. With the pressure regulator valve removed, inspect for a missing orifice cup plug in the end of the valve (refer to Figure 1).

3. If the cup plug is missing, inspect the pressure regulator valve bushing as well as the transmission case for the original plug, and remove it if found.

4. Inspect a new pressure regulator valve (P/N 8623422) to be sure the orifice cup plug is present before installing the replacement valve into the transmission.

5. Inspect and install the pressure regulator valve by using Step Nos. 1 through 14 under the heading "PRESSURE REGULATOR" on pages 325-4L-65 and 67 of the 1983 Service Information Manual.

6. Install the transmission oil pan with a new gasket (P/N 8635014), torque all fasteners to 9.0-13.0 N.m (7-10 ft. lbs.) and add transmission fluid as required.

For warranty purposes, use Operation T6065 at .7 hour.

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.