Part of the car's engine cooling system, the thermostat has an important part to play in ensuring the engine stays at the right temperature for optimum performance, power and efficiency. The thermostat functions to prevent the movement of liquid coolant into the radiator until the engine has reached the correct temperature and allows the coolant to flow into the radiator when the engine needs cooling down. The thermostat housing functions to house and protect the thermostat.

The thermostat lies between the engine and the radiator, in the thermostat housing, sealed tightly with a thermostat housing gasket. Circular in shape and manufactured from either felt, sponge, metal, or cardboard the thermostat gasket forms a firm seal.

The thermostat, based on the temperature of the engine, will either open or close, acting as a valve, enabling or preventing the coolant to flow into the radiator. If the temperature of the engine is too cold, the thermostat remains shut, keeping the coolant out of the radiator. If the engine temperature is too hot, the thermostat opens, allowing the coolant to flow in. The thermostat opens to release the flow of coolant into the radiator when the engine has warmed up to the right temperature. By waiting until the engine is fully warmed up before releasing the coolant, the thermostat is enabling the engine to warm up as quickly as possible, which helps the engine to perform better and helps to reduce wear and tear on engine components, prevent deposits and reduce harmful emissions. The thermostat functions to stop the car engine from overheating, by opening to enable coolant to travel into the radiator. The thermostat housing plays a crucial role in helping to protect the thermostat and ensure that the car runs at a proper working temperature. The thermostat housing gasket is crucial in providing a tight seal between the thermostat and thermostat housing to help prevent leaks.

A sign of a failed thermostat or a fault with thermostat related components such as the thermostat housing gasket is an engine that overheats or an engine that doesn't reach the right heat for correct engine operation. If corroded or cracked the thermostat housing should be replaced as the thermostat could get damaged. If the thermostat/thermostat housing is leaking coolant this is most likely due to a worn thermostat gasket. Damaged or old thermostat gaskets should be replaced. Consulting with your mechanic to make sure the correct fault has been found is a good idea before purchasing replacement parts. When replacing this part, choosing to fit a good quality thermostat will guarantee compatibility with the make and model of your vehicle.