Water Pump and Pulley Identification and Usage Information

Whenever it is necessary to service any of the above listed models, you may notice differences in the water pumps, pump pulleys, & gaskets (used to seal the pump to the engine block).

The 1997-99 water pumps have had design changes that took place at various intervals during production.

1. 1997-98 water pumps (1) have longer legs (the area used for attaching the pump to the block), paper gaskets, and a bolt on pump pulley (4).
2. 1999 first design pumps have shorter legs, carrier type gaskets, and a bolt on pump pulley.
3. 1999 second design pumps (2) have shorter legs, carrier type gaskets, and a press on pump pulley. This design pump and gasket set can be used on all model year LS1 aluminum engines.

When servicing the pump, the appropriate model year kit should be used from GMSPO. The 1997-98 long leg pump (1) will be phased out Service Parts, and the second design 1999 pump (2) will supersede it. The 1999 first design pump with the bolt on pulley is not available for service. Use of the second design will be necessary upon pump replacement.

Notice: It is important to use the proper gasket (paper or carrier) with the specific design water pump. Using an incorrect type gasket will mis-position the serpentine belt on the water pump pulley and belt damage will occur. The aluminum carrier gaskets (3) cannot be used with the 1997-98 long leg pump (1), due to belt alignment concerns. The paper gaskets cannot be used with either 1999 model, short leg pump, due to belt alignment concerns.

Parts are currently available from GMSPO.