The water pump
is an impeller or centrifugal pump that forces coolant through the engine block, cylinder
head, intake manifold, hoses, and radiator (fig. 6-7).
It is driven by a fan belt running off the crankshaft pulley.
parts of a typical water pump include the following:
PUMP IMPELLERa disc with fanlike blades that spins and produces pressure and flow.
PUMP SHAFTsteel shaft that transfers turning force from the hub to impeller.
PUMP SEALprevents coolant leakage between pump shaft and pump housing.
PUMP BEARINGplain or ball bearing that allows the pump shaft to spin freely in the
PUMP HUBprovides mounting place for the belt and fan.
PUMP HOUSINGiron or aluminum casting that forms the main body of the pump.
The water pump
normally mounts on the front of the engine. With some transverse (sideways) mounted
engines, it may bolt to the side of the engine and extend towards the front.
A water pump
gasket fits between the engine and the pump housing to prevent coolant leakage. RTV sealer
may be used instead of a gasket.
the water pump is as follows (fig. 6-8):
spinning crankshaft pulley causes the fan belt to turn the water pump pulley, pump shaft,
trapped between the impeller blades is thrown outward, producing suction in the central
area of the pump housing.
the pump inlet is near the center, coolant is pulled out of the radiator, through the
lower radiator hose.
being thrown outward and pressurized, the coolant flows into the engine. It circulates
through the block, around the cylinders, up through the cylinder heads, and back into the
Figure 6-7.Water pump.
Figure 6-8.Water pump operation.