The engine is cooled by a coolant mix, which circulates around the engine to absorb heat. The coolant flows through the radiator, an automotive air-cooled heatsink, where the heat is dissipated for the return trip back through the engine. Your vehicle's water pump drives this circulation cooling process.
Cooling system problems are the number-one mechanical failure. After many thousands of miles and years of pumping coolant, water pumps eventually wear out. You might notice a whining or grinding sound coming from the water pump, or may even see coolant leaking from the water pump.
The precise location of the water pump varies depending on the vehicle. Some have the water pump attached to the outside of the engine where you can see it, which may be driven by a serpentine belt.
Some have the water pump driven by the timing belt, which the timing belt cover often hides these water pumps. When you have us replace the water pump on one of these vehicles, you should replace the timing belt at the same time (and vice versa). We need to take many things apart and the belt is most likely contaminated by coolant. Timing belts usually need to be replaced every 60,000 to 90,000 miles, so replacing both at the same time is pragmatic and can help save you more money soon after.