ENGINE OVERHEAT/DAMAGE REVERSE ROTATION WATER PUMP

VEHICLES AFFECTED: 1987 S,T,M, AND G MODELS WITH SERPENTINE BELTS

All 1987 S, T, M, and G model trucks with serpentine belt drives use a reverse rotation water pump (water pump rotates opposite the crankshaft), see Figure 1. The reverse rotation water pump has the same appearance as a "same direction" water pump, see Figure 2.

When servicing 1987 water pumps on trucks with serpentine belt drives, care must be taken to use only the part specified in the parts book. The usage of the incorrect water pump can cause engine overheat and possible engine damage.

The water pumps can be identified by using the following information:

4.3L/ 5.OL, 5.7L REVERSE ROTATION WATER PUMPS have no bracket mounting bosses on the top of the pump housing. The pump casting number is 14102026.

4.3L, 5.OL, 5.7L SAME DIRECTION WATER PUMPS do have bracket mounting bosses on the top of the pump housing. The pump casting number is 376444.

2.8L REVERSE ROTATION WATER PUMPS have three bolt attachments on, the bottom of the pump housing.

2.8L SAME DIRECTION WATER PUMPS have four bolt attachments on the bottom of the pump housing.

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.