Pump Vibrating or Overheating

Engine speed too high

Obstruction in pump casing / impeller

Impeller damaged

Cavitation due to excessive suction lift

Suction or discharge re-circulation of fluid within the pump

Impeller out of balance

Shaft bent

Shaft running of centre because of worn bearings or misalignment

Misalignment

Bearings worn

Pump not primed

Pump or suction pipe not completely filled with water

Inlet of suction pipe insufficiently submerged

Excessive thrust caused by mechanical failure inside pump

Lack of bearing lubrication

Incorrect assembly of stacked bearings, i.e. angular contact ball bearings fitted front-to-front instead of back-to-back

Dirt in bearings

Rusting of bearings from water in housing