What Causes Water Pumps to Fail?

Water pumps can fail prematurely due to corrosion inside the cooling system or from an imbalanced water-pump shaft. But in most instances, water pumps fail because of shaft leaks.

If a water pump is expected to last 100,000 miles without any issues, that’s about 110 average-size swimming pools one little pump would fill in its lifetime. It’s hard to imagine that a pump could last so long – and many do – but many fail prematurely due to other cooling-system factors.

Water pumps can fail prematurely due to corrosion inside the cooling system or from an imbalanced water-pump shaft. If there’s a mechanical fan mounted on the water-pump shaft, vibrations are the result of a bent fan blade, which can lead to the shaft cracking or breaking. A bent pulley also can cause the same damage. Excessive tension on a fan belt or serpentine belt also can overload the water-pump shaft bearings and cause the pump to fail. But in most instances, water pumps fail because of shaft leaks.