What does the thermostat do and what typically happens if it fails?

What is a thermostat
A Thermostat Is a device which senses the temperature of a control system and maintains the temperature within a fixed limit by using cooling and heating systems. It also controls the drift of heating fluid to limit the level of temperature near a definite point. The Thermostat makes use of multiple sensors to sense heat and thereby uses other systems to maintain it.

How does it work
The thermostat constitutes of a cylindrical body located near the engine of the car. This body has fax filled in it which begins to melt at around 180 degrees Fahrenheit (melting point of wax). A shaft which is banded together with a valve starts pushing into the melting wax. When the wax melts completely it expands and forces the shaft out of the cylinder, thereby unsealing the valve.

What does thermostat do
All car engines comprising of liquid cooling system consist of a thermostat located between the radiator and the engine. When you start the engine of your car, the position of the thermostat is a state of blocking the refrigerant from flowing towards the radiator. This means that the coolant does not flow till the engine is cold. As soon as the engine warms up and starts operating at its standard temperature, which is about 200 degrees Fahrenheit, the thermostat loosens its valve and opens. By doing this it helps the engine to get to the standard working temperature soon. Warming up of the engine quickly every time it is started results in less deposits and emissions. Along with this, it also increases the life of the engine.

Why does it fail
The thermostat is a device which controls the flow of coolant in the engine. When a thermostat fails to perform the above said function, it is said to have been failed. This happens when it is stuck blocked and is unable to open the valve. This prevents the coolant to flow to the engine because of which there is an overheating of the engine.

There are three types of thermostat failures.
The first one is Thermostat stuck closed. During this failure, the piston and the wax combination stops functioning as a result of which the wax is not able to keep the valve closed when it needs to be. Thermostat stuck closed is a condition in which the element of the wax is either damaged or broken due to overheating.

The second one is Thermostat stuck open. During this failure, the thermostat is not able to close the valve when coolant flow has to be stopped because of which the engine requires much more time as compared to normal to reach the optimum temperature. It is also possible that the engine doesn’t achieve the normal working temperature in case the atmospheric temperature is too low. Thermostat stuck open is a condition in which the coolant flows to the engine when it is still cold. The main reason of this type of thermostat failure can be the binding back of the sensor, broken recoil spring or some junk sticks in between and restrict the closure of the valve.

The third one is the thermostat stuck half way. This is the most common failure any engine may face during its operation. This type of failure happens either when the shaft of the piston is jammed halfway or the wax may not fully expand and thus fails to accomplish the task of opening the valve.

However if any of the above condition rises, you should not panic. You can always get the problem fixed or replace the thermostat before it can damage any of the machines.