EXAMPLES OF WATER PUMP FAILURE MODES David Lewis Jan 2014

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

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

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

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

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

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

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

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

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