Symptoms of a Bad Cooling System Water Pump

 We are a team of ASE certified mechanics that have created this guide to let you know the symptoms of a failing cooling system water pump, this will result in the engine creating noise, overheating or breaking the serpentine belt.

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  1. The water pump is designed with a weep hole to allow coolant to leak from its housing before it can reach the shaft bearing which will cause the shaft to lock up and stop turning. If this shaft locks up it will cause the serpentine belt to break which will cause a break down. It's typical for the pump shaft seal to leak while the engine is running, and then stop leaking once the engine has been shut off. When the coolant level inside the engine diminishes the engine will overheat which can cause the block or cylinder heads to crack. It is difficult to replace the water pump seal by itself which is why in most cases the water pump must be replaced.
  2. The water pump is designed with two shaft bearing which support the main shaft of the pump. When these bearings go out they can cause a squeaking, ticking or grinding noise because the shaft bearings are trying to lock up within the pump housing, (sometimes a failing water pump will be silent). This bearing failure is due to corrosion or the pressure being applied to the pulley by the serpentine belt or the timing belt or chain. If the water (coolant) pump is not replaced it can cause the pump to lock up which will derail or break the serpentine belt. Below is a water pump being driven by the serpentine belt and the tension being applied by the belt tensioner. To check the water pump shaft bearings remove the belt and grasp the pulley or fan and move it side to side, there should be little to no play within the shaft bearings and the housing. An additional method to check the bearings is to look straight down at the pulley and see the alignment of the pulley with the other pulleys of the engine. If the water pump pulley is noticeably offset then you know the bearings are bad.
  3.  The operation of the water pump is to circulate coolant throughout the radiator and cooling system, if the impeller of the pump has an issue this circulation stops and the engine will overheat. To check for this condition lower the coolant level a few inches so you can see the radiator cooling tubes, with the radiator cap off warm the engine, when the engine reaches operating temperature you should be able to see coolant flowing from the tubes if not this could be the failure. In the image below you can see the impeller has dislodged itself from the main shaft.

Questions?

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