Water Pump Problems

WATER PUMP PROBLEMS



Leaking Water Pump - As a water pump ages, the seal and bearings begin to wear allowing for leakage around the shaft. Improperly installed gaskets may also be a source for leakage.

Eroded/Separated Impeller - Severe corrosion may cause one or more blades to become separated from the impeller. In extreme cases the entire impeller may become separated from the water pump shaft.

SYMPTOMS
Leaking Water Pump
- Coolant leaking from the shaft or from the inspection hole.
- A growling noise coming from the worn water pump bearings.

Eroded/Separated Impeller
- Engine overheats with no visible causes:
- Coolant is full, with no leaks.
- Cooling fan operates properly.
- Water pump belt is intact.
- Thermostat may operate properly (depending on the extent of damage to the impeller).

HOW TO VERIFY
Leaking Water Pump
- Pressurize the cooling system and inspect the shaft and inspection hole for coolant seepage.
- Start the engine and allow the cooling system to warm up to normal operating temperature. Stop the engine and reinspect the water pump for leakage.

NOTE: If the seals are just beginning to wear out the water pump may only leak while the engine is running and shaft is turning.




- With the engine stopped and the ignition key removed, check the water pump pulley for wobble. If any lateral movement is detected the pump should be replaced.

NOTE: Verify the pulley is securely fastened to the shaft prior to replacing.

Eroded/Separated Impeller
- Check and fill radiator if necessary.
- Verify no coolant hoses are kinked or obstructed.
- Verify the thermostat and cooling fan operation.

WARNING: Do not allow the engine to overheat.

NOTE: A plugged radiator and an eroded/separated water pump impeller will exhibit many of the same symptoms. If the radiator is plugged there may still be flow across the heater core while if the water pump impeller is eroded or separated neither the radiator or the heater core will have flow.

- With the engine running and warmed up to normal operating temperature, check for coolant flow through the radiator and heater core:

Heater Core:
- Turn the heater on (with temperature control to "HOT") and turn the fan to "HIGH" speed.
- If flow exists the inlet hose should be 15-20° warmer than the outlet hose.
- If no flow exists both hoses will be the same temperature.

Radiator
- With the cooling fan on and the thermostat open, compare the temperatures of the upper and lower radiator hoses.
- If flow exists the upper hose should be 15-20° warmer than the lower hose.
- If no flow exists both hoses will be the same temperature.

WARNING: Use a surface thermometer or infrared temperature gun to determine hose temperature. Do not attempt the feel the temperature by hand, this may result in serious personal injury.