Cooling System Servicing: Description

Basic liquid cooling systems consist of a radiator, water pump, thermostat, cooling fan, pressure cap, heater, and various connecting hoses and cooling passages in the block and cylinder head. Many vehicles use a clutching fan, which may incorporate thermostatic control, or a flexible blade fan, or both, to reduce noise and power requirements at high engine speeds.

Some vehicles use a thermoswitch (or thermoswitches) usually located in the radiator tank to activate electric cooling fan(s). Many vehicles with transversely mounted engines use this system. For a better exhaust emission control system, some vehicles use a thermostatic vacuum switch to advance ignition timing in case of overheating.

As most new models require use of permanent, year round (ethylene glycol) type anti-freeze, coolant recovery systems are being used more commonly to prevent coolant loss. Requirements for antifreeze have changed due to materials used in engine manufacture.