What Does a Car Thermostat Do?

A car thermostat is a vital link in a vehicle's cooling system. Although small in size and inexpensive, a thermostat provides a variety of engine and cooling system functions, functions that are extremely important to the overall operational efficiency of a vehicle. What follows is a brief list describing the many functions of a thermostat.

Links the Engine and Radiator

On most vehicles, a thermostat is located in the upper radiator hose, a hose that links a vehicle's radiator with the its engine block. A thermostat is designed with a small internal plunger mechanism that controls coolant flow into and out of a vehicle's engine.

Prevents Engine Overheating

A thermostat also keeps an engine from overheating by opening and allowing heated engine coolant to flow into the radiator, which cools the engine coolant, thus reducing engine operating temperature.

Reacts to Coolant Temperatures

Being a heat-sensitive valve, a car thermostat is designed to react to changing engine coolant temperatures. Most vehicles have thermostats that are designed to open at pre-set engine coolant temperatures, such as 180, 195 or 210 degrees F.

Speeds Engine Warm-Up

A car thermostat is a heat-sensitive valve that opens and closes in response to changing engine coolant temperatures. When a cold vehicle engine is started, the thermostat closes and stops engine coolant from flowing out of the engine and into the radiator, a process which facilitates engine warm-up.

Prevents Engine Underheating

The proper function and operation of a car thermostat helps to regulate engine operating temperatures. A thermostat prevents an engine from staying too cold by closing and locking engine coolant inside a vehicle's engine, which speeds engine warm-up.