Cooling System Servicing: Description

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

Some models use thermoswitch located in radiator tank to activate electric cooling fan(s). This system is usually found on vehicles with transversely mounted engines. Due to exhaust emission control, some vehicles use 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.