New THM 700-R4 transmission oil pump assemblies with nodular iron vane rings. The new design vane rings will reduce the possibility of vane ring breakage.
DATE OF PRODUCTION CHANGE: (Figure No. 1) ------------------------- Beginning April 28, 1987 (Julian date 118) all 1987 THM 700-R4 production transmissions and Service Replacement Transmission Assemblies (SRTA) were produced with new nodular iron vane rings.
The new design pump vane rings (Figure No. 2, Item 212) can be used on any of the above models. The past design vane rings can only be used on 1982 through 1987 THM 700-R4 transmissions. It is recommended that the new iron pump vane rings be used when replacement of the vane rings becomes necessary.
THM 700-R4 transmissions only:
8657531 Pump Vane Ring (2 Required)
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.