THE AUTOMOTIVE WATER PUMP
by Jim Miller

The cooling system of an automobile is what prevents your vehicle from overheating and thus possibly causing the engine to seize. If there wasn't a means to cool things off, the engine would become a block of useless metal in short order. The parts which make up the cooling system have a single goal - moving coolant/water around the engine block so it will dissipate heat. A basic automotive cooling system is made up of the following components:

- Radiator
- Radiator Hoses (top and bottom)
- Thermostat
- Thermostat Switch
- Cooling Fan (located behind the radiator)
- Water Pump

The water pump circulates coolant throughout the engine. Water pumps use a rotating vane called an impeller, that forces coolant outward at pressure. As the coolant is forced out towards the outer wall of the water pump, low pressure is created at the inlet of the water pump allowing coolant to flow into the water pump. The pressurized coolant is forced out of a passage and through the engine cooling system where it returns to the water pump.

Water pumps are generally placed on the front of an engine and are driven with pulleys and a belt using the crankshaft as a means of rotation. There are some variations on this design using a timing belt or timing chain to rotate the water pump impeller. The water pump inlet in a normal flowing cooling system, is attached to the radiator to intake low temperature engine coolant. Some water pumps contain an extra inlet where coolant from the heater core returns to the water pump as well.

Water pumps can be subject to seal and bearing failures. A loose water pump shaft can indicate a worn impeller bearing. Fluid leaking from the shaft outlet or the water pump weep hole can indicate a seal failure.

When beginning an auto repair project involving an overheating engine, of course, one of the first things you should always check is the water pump.

(Jim is a lifelong fan of Dodger Baseball and used to race sprint cars in the 1980s.)