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Cooling System Thermostats - Select your Make

Thermostat Information

Coolant Thermostats
The thermostat consists of an outer body that houses a temperature-sensitive paraffin based valve that opens and closes based on the vehicles coolant temperature. Most thermostats operate off coolant temperature, but some cars and trucks use computer-controlled thermostats that are controlled by the powertrain control module (PCM). The thermostat can be located on the top of the engine, in the outlet going to the radiator and some may be mounted towards the bottom of the engine near the radiator hose inlet to the engine. Cooling system is rated in degrees that reflect the typical cooling system temperature maintained by the thermostat.

You can purchase thermostats in varying degrees based on the environment or the type of driving you are doing. The thermostat is the engine cooling systems temperature control. When the engine is cold, the thermostat stays closed and keeps coolant from flowing thru the radiator. This enables the engine to warm very quickly. As the coolant increases in temperature the paraffin element causes the valve in the thermostat to open slightly, allowing some of the coolant to flow thru the radiator. As the engine coolant continues to increase, the thermostat opens more in relation to the heat of the coolant. Under normal operating conditions with a fully warmed engine, the thermostat will be completely open.

The thermostat is a very critical part of the cooling system that can cause many symptoms and problems. An open thermostat can result in low heater output, overheating and poor fuel economy. A thermostat that does not open or open all the way can cause knocking or pinging when accelerating and overheating. A faulty thermostat can even cause your car to fail an emissions test.