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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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.
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.
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.