Standard vs. Reverse Rotation
When determining if a water pump is STANDARD or REVERSE rotation, refer to the belt path diagram under the vehicle’s hood on most late model light trucks and automobiles. The diagram will typically be located on the fan shroud, or on the front fender brace. Find the water pump pulley on the diagram (or look on the front of the engine if you cannot find the diagram). Otherwise, locate the water pump pulleys on the vehicle. Simply determine if the water pump is driven by the outside or inside of the belt.
Compare the diagram below.
- Water pump pulleys running on the INSIDE surface of the belt indicate a STANDARD ROTATION water pump.
- Water pump pulleys running on the OUTSIDE surface of the belt indicate a REVERSE ROTATION water pump.
WARNING: STANDARD AND REVERSE ROTATION WATER PUMPS ARE NOT INTERCHANGEABLE. Serious engine damage can result from using the wrong pump.