Water Pump Diagnosis

A 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.

1. Remove cooling system pressure cap.
2. Remove a small amount of coolant from the system.
3. Start the engine and warm up until thermostat opens.
4. With the thermostat open and coolant level low, visually inspect for coolant flow. If flow is present, the water pump is pumping coolant through the system.