7. Damaged or broken shaft
Appearance: The shaft is bent or broken. A clean break indicates an “instantaneous” fracture caused by sudden overload or imbalance. If the broken shaft is discoloured (usually blue), the damage was gradual, indicating excessive heat build-up before the shaft broke.
Cause: A misaligned belt causes excessive wear. An over-tensioned belt imposes a powerful bending force on the shaft resulting in shaft bending or early shaft fracture. Excessive vibrations due to lack of maintenance.
Solution: Replace the water pump and make sure to inspect the belt drive system: belt, tensioner, pulleys, belt tension and alignment. If equipped with a water pump mounted fan, inspect the fan/fan clutch assembly. The fan may not be squarely mounted on the shaft. A bent or damaged fan, a worn spacer, or a worn or damaged fan clutch could also be factors contributing to the break.