1. EXAMPLES OF WATER PUMP FAILURE MODES
David Lewis Jan 2014

2. Failure modes Corrosion Cavitation and Erosion Electrolysis
Body damage (Cracking)
Dirt or incrustations
Excessive use of gasket sealant
Impeller cracks
Overload (Tension)

3. Corrosion CAUSE Use of Non specified manufacturer coolant
Top up with Water only
RESULT
Rust contaminates the cooling system and results in leakage.

4. Cavitation and Erosion
CAUSE
Incorrect bleeding of cooling system
Temperature exceeds boiling point
RESULT
Loss of flow, holes in casting leading to leakage

5. Electrolysis CAUSE Low PH value causes acidic action.
Incorrect coolant
RESULT
Reduced flow and over heating

6. Body Damage (Cracking)
CAUSE
Over tightening of bolts
Non sequential tightening of bolts
Porosity (Unlikely)
RESULT
Unable to fit pump
Pump leaks in service

7. Dirt or Incrustations CAUSE
Engine not flushed out when changing cooling system components
RESULT
Damages the surface of the mechanical seal.

8. Excessive use of gasket sealant
CAUSE
Over application to ensure it fits first time and doesn’t leak
RESULT
Sealant strands detach and force themselves between the unitised seal

9. Impeller Cracks CAUSE Poor handling of pumps RESULT
Loss of interference between impeller and centre spigot
Gradual erosion of the impeller

10. Overload (Tension) CAUSE
Don’t follow vehicle manufacturers instruction
Belief in Automatic tensioners
Result
Bearing failure
Extreme Engine damage (Particularly in synchronous drive)