Water Pump Diagnosis

A quick test to tell whether or not the pump is working is to see if the heater warms properly. A defective pump will not be able to circulate heated coolant through the long heater hoses. For water pump inspection, refer to Water Pump, Cleaning and Inspection for procedures. The water pump on all models can be replaced without discharging the air conditioning system.

NOTE: It is normal for the water pump to weep a small amount of coolant from the weep hole (black stain on water pump body-3.2/3.5L, or at weep passage below the thermostat housing-2.7L). Do not replace the water pump if this condition exists. Replace the water pump only if a heavy deposit or a steady flow of engine coolant is evident on water pump body (3.2/3.5L), or from the weep passage (2.7L). This condition indicates a shaft seal failure. Be sure to perform a thorough analysis before replacing the water pump.