All 1987 THM 400 transmissions have a new latex-coated cellulose (hard, fiber material) pan gasket. The new gasket improves sealing because it will not "Crush'cts like a cork (soft material) gasket.
DATE OF CHANGE: (Figure 1)
July 22, 1986 (Julian Date 203) for all 1987 THM 400/475 transmission models.
The previous latex-coated cork (soft material) gasket, in some service overhaul packages, should NOT be used. The new gasket is available separately and can be used on any model year THM 400/475 transmission.
SERVICE PARTS INFORMATION:
PART NUMBER DESCRIPTION
8655625 Gasket, Transmission oil Pan (Cellulose)
SERVICE MANUAL REFERENCE:
Refer to the Oil Pan and Filter Assembly section of the 1987 THM 400 Unit Repair Service Manual for proper installation procedures.
When installing the oil pan you must use a torque wrench to tighten the conical washer and screw assemblies to 8-14 N.m. (6-10 ft. lb.).
Report any case(s) of oil pan leaks on a 1987 THM 400/475 transmission using the new cellulose pan gasket to your vehicle division's 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.