ALT-1 Understanding how a Vehicles Water Pump Works
The water pump is the most vital part of the cooling system on a vehicle. It's only function is to circulate the coolant through the entire engine and the heater core, and then push the coolant through the radiator and back to the pump.
There are two basic ways that the pump is driven. First, it is spun by the serpentine belt while the engine is running. This serpentine belt also drives the alternator, power steering pump, and the air conditioner compressor (if equipped). In older vehicles, there were as many as 3 belts driving the separate components, with one dedicated to driving the water pump. The second is the pump pulley being spun by the timing belt while the engine is in operation. This style is most common with the import vehicles. Both types of water pumps operate in the same fashion and have the exact same job.
Both types have vanes much like a windmill, only on a much smaller scale. These vanes operate by doing two things as they are spinning. They draw colder coolant into the pump through the lower radiator hose and push it into the engine through a passage into the engine block. Since these vanes are spinning at a very high rate, it creates pressure forcing the coolant through the entire system. Creating this pressure is the essential key to water pump operation and keeping your engine from overheating. Without the pressure, there is no circulation. Without circulation, there is no cooling. Without the cooling, you have costly repairs ahead due to overheating.
