In a car’s cooling system the water pump is the driving force that keeps the car cool. Unlike the radiator which just sort of sits there and lets the coolant travel through its tubes, the water pump is an active participant in the cooling process. Without the pump doing its job the system would fail and surely overheat.
Depending on the period of manufacture of the vehicle, the pump is usually made of cast aluminum or cast iron. It is mounted on the front of the engine block on a traditional “in line” motor set up with the radiator staring it in the face. The water pump can also be to the side of the engine compartment on a car with a transverse engine, in this case it would be extremely rare to see the radiator directly in front of the pump.
There’s one sure way to find the water pump under your hood, and that’s to follow the belts. To my knowledge all water pumps are belt driven which is a good thing except in certain situations. The pump can have a shaft attached to it on which is mounted the cooling fan. This is the arrangement on a vehicle that uses the same energy that drives the pump to move air through the radiator to dissipate the heat in the coolant via the fan. The other set up is to use an electric cooling fan to move the air, in this case there is no shaft and no fan attached.
The way the water pump works is fairly straight forward. The pump, powered from the energy of the car’s engine, which is transmitted through the belt, “picks up” coolant supplied to it through a hose and pushes it through the cooling system. The coolant then follows a continuous route through the engine to keep it cool and at the same time rising in temperature. It makes it way to the radiator where it cools down and back to the water pump where the cycle starts all over again.
All this works well except when the belt breaks. Without the belt the driving force is like an office worker on Mondays without any caffeine – no energy- and in the case of the water pump not moving any coolant. The car is certain to overheat as the cooling fluid sits in the engine block and cooks, boils is a more accurate description. But don’t obsess over this possibility, since most belts these days drive multiple accessories and a broken belt would most likely render the car inoperable thus preventing you from overheating to the point of engine damage. Regardless you should be monitoring the gauges which would keep you out of trouble.
A water pump can also leak as the seal that prevents coolant leaking past the bearing degrades over time and fails. The obvious symptom is for fluid to appear on the pavement. Not recognizing or ignoring the leak results in overheating as the remaining coolant becomes insufficient to cool the engine.
Like any other part on a car, when it’s doing its job the water pump becomes a silent partner as it plays it vital role. But when things get hot under the hood and the immediate future is in doubt, it’s sure to make its presence known.