Component Tests and General Diagnostics
OPERATIONAL TESTA quick flow 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 hose. Another flow test to help determine pump operation.
WARNING: DO NOT remove radiator cap if the cooling system is hot or under pressure.
FLOW TEST
1. Remove radiator cap.
2. Remove a small amount of coolant from the system, start the engine and warm up until thermostat opens. With the thermostat open and coolant level low you will see if the water pump is pumping coolant through the system.
REASONS FOR REPLACEMENT
Replace water pump body assembly if it has any of these defects:
1. Cracks or damage on the body.
2. Coolant leaks from the shaft seal, evident by coolant traces on the pump body.
3. Loose or rough turning bearing.
4. Impeller rubs either the pump body or the engine block.
5. Impeller loose or damaged.
6. Sprocket or sprocket flange loose or damaged.