A cars thermostat regulates the engines coolant temperature and keeps it at a desired level. How does it do that? By controlling the heating or cooling mechanisms so that the temperature is maintained at a constant level.
What it does is to keep a control of the heat that flows into the system or out if it. Automotive thermostats are used to control the flow of the coolant in the internal combustion engine and there are different thermostats for different temperatures. You’ll find thermostats in any liquid-cooled engine.
When the engine is warming up, this small device which you’ll find between the radiator and the engine, remains closed. This ensures that the coolant does not go from the engine to the radiator until the desired temperature is reached. Once that happens, this spring-like device opens up and lets the coolant flow into the radiator to cool it. Thanks to this, the engine maintains a fairly constant temperature without the fear of it overheating.
Many of the auto thermostats used depend on wax pellets which melt and expand as the engine warms up. This makes the valve open. Today, a lot of the new digital thermostats have thermistors instead of moving parts. These need batteries installed in order to operate them.
The performance of the thermostat could be affected by the water pump failing or the engine overheating or even leakage of the coolant. So it is very important to get your thermostat checked on a regular basis. Since it plays such an important part in the cooling of the engine, it must be replaced regularly, say once every couple of years, which is fine as it is a relatively inexpensive piece of equipment.
If you do not replace the thermostat when it should be replaced, you could have problems like poor fuel economy, or knocking when accelerating and your heating system may not work as well as before. Worse, you could even have a problem with emissions. So it makes sense to replace it when needed.