OIL PAN GSK.FLUID LEAKS NEW CELLULOSE OIL PAN GSK.

Bulletin Covers:

On the Julian Dates listed below, all 1986 THM 200C and THM 200-4R transmissions were built using a new latex-coated cellulase (hard, fiber material) pan gasket. The new gaskets improve sealing capability by better withstanding fastener torques.

Date of Production Change: (Figures 1 and 2)

THM 20OC: May 29, 1986, Julian Date 149, New Cellulose coated transmission pan gasket implemented.

THM 200-4R: June 23, 1986, Julian Date 174, New cellulose coated transmission pan gasket implemented. Service Action:

Any model year THM 200C and 200-4R transmissions with a continuous raised rib pan can be serviced with the new cellulose gaskets. When servicing a THM 200C or THM 200-4R which has the former flat surface pan, refer to Product Service Bulletins 84-7-122 (THM 200-4R) and 83-7-213 (THM 200C) for proper service procedures.

Some service overhaul packages may contain the latex-coated cork (soft material) gasket, which should not be used. The new gasket can be ordered separately by ordering the appropriate part number listed below.

Service Parts Information:

8648529 THM 200C Gasket, Transmission Oil Pan (Cellulose)

8657387 THM 200-4R Gasket, Transmission Oil Pan (Cellulose)

Service Manual Reference:

Refer to the Automatic Transmission Unit Repair sections of the respective 1987 Service Manuals for proper installation procedures. Service Notes:

When replacing the oil pan it is critical that a torque wrench is used to tighten the hex head pan screws. Hand torque all THM 200-4R hex head screws 8-14 N..m. (6-10 lb. ft.) and all THM 200C hex head screws 10-16 N.m. (7-12 lb. ft.). Note: The THM 200C pan torque specifications have recently been changed from 8-14 N.m. (7-12 lb. ft.). Please update page 20OC-43, of the THM 200C Unit Repair Section in your 1987 Service Manual, to reflect this change.

Report any case(s) of oil pan leaks on 1986 THM 200C or 200-4R Transmissions using the new cellulose pan gasket through the Product Information Reporting system.

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.