Tech Tips

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Cooling System

Checklist for Water Pump and Fan Clutch Problems

HOW TO TELL IF A WATER PUMP IS DEFECTIVE
Check for shaft seal failure by carefully inspecting the water pump weep hole. When a water pump is new, some seepage is normal in the initial hours of operation as the seal seats. Other than that, any leakage that occurs is due to seal failure and the pump needs replacement. There may be tell tale trails of rust, calcium and coolant deposits on the water pump housing with the weep hole as the origin.

Detect a worn water pump bearing by checking for side-to-side play at the shaft. There should be no perceptible play as you apply hand pressure to the shaft. Accelerated bearing wear is characterized by screeching or rumbling noises coming form the water pump housing. If any of these conditions exist, the bearing is worn out and the pump should be replaced.

HOW TO TELL IF A FAN CLUTCH IS DEFECTIVE
Check for oil streaks (or dust collected on oil streaks) on the fan clutch. It's a sure sign that the internal fluid that provides the clutch action is leaking.

To check for a worn bearing, with the engine off, grasp the fan blade on either end and check for lateral movement. If there's more than 1/4" of side-to-side movement, the bearing is worn and the unit needs replacement.

In checking for proper fan clutch operation, first run the engine until operating temperature is reached. Next, with the engine off, give the fan blade a gentle spin. If it rotates more than twice the clutch is worn and needs replacing. If fan rotation is rough or noisy, or the fan fails to turn, the unit is worn out and needs replacement.

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