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