How Does a Car Thermostat Work?
A car thermostat is an essential part that plays a key role in keeping the engine running without overheating. If ignored, a bad thermostat can lead to severe engine damage. As car engines operate in between 75 to 100 °C, coolants are required to keep the temperature in check and below the threshold.
In the article, we will take a look at the role of car thermostat and how it protects our engine from damages due to overheating.
Car Thermostat and Radiator

A car thermostat is like a barrier between the radiator and the engine. It allows the flow of coolant when needed. To understand how it works, let us consider a simple engine connected to the car radiator thermostat. The coolant must be circulated through the engine to absorb heat and loops back to the radiator to cool off.
The radiator is made up of multiple aluminium tubes and fins. To make fluid cool off faster, fins are inserted into tubes to create turbulent flow. Fluid touching the tubes transfers the heat and is cooled off by blowing air through a fan.
In most radiators, the coolant outlet is at the bottom and controlled by a thermostat valve. The water pump pulls the coolant to loop it back to its upper inlet.
Function of Car Thermostat
A car thermostat is basically a valve, and its function is to stop or allow the flow of coolant into the engine according to the temperature differences. To understand its function better, let us consider two case scenarios:
When a car engine is cold, the thermostat valve will close itself to prevent any coolant from leaving the system back to the radiator. This allows the engine to warm up faster as the existing coolant will also heat up to expedite the process.
In case you have overheating car engine, based on optimum running temperature, the thermostat valve will open. As the new coolant starts to circulate to cool down the engine to safer temperature. The warm coolant is cycled back to the radiator for cooling to repeat the process.
Symptoms of Failing Car Thermostat
Now that we know how a car thermostat works, let’s find out how to identify a bad car thermostat. The lifespan of a car thermostat can easily cross 10 years or more. Hence, it’s not easy to answer how long a car thermostat lasts.
The following signals should give an idea of when to replace a car thermostat:
Engine Overheating
Among the many causes of car engine overheating, the primary cause is usually related to the radiator including the thermostat. For instance, if the thermostat valve is stuck in a closed position, fluid is unable to circulate and cool down. If the engine is left running, there is a risk of some major damage.

However, apart from the car thermostat, other causes may include lack of coolant, failure of the water pump or radiator leakage as well.
Engine Failure to Warm Up
A car’s heater might not work properly if the thermostat valve is stuck in an open position or is deteriorated. Since the fluid circulates nonstop, the engine is unable to maintain its optimum operating temperature. This can lead to performance issues leading to poor fuel economy and accelerate the wearing of engine components.
Engine Temperature Fluctuation
Temperature fluctuation happens when the thermostat valve is unable to hold its position (open or close). This can lead to false temperature readings and affect the proper circulation of coolant.
Low Engine Performance
As we already know how car thermostat can affect an engine’s performance. Since many factors can lead to low performance, be sure to check for a faulty thermostat before going for further diagnostics.
Driving on a faulty thermostat might result in engine failure in the middle of the road. To top it off, it’s even more expensive if repair work is required on the radiator and engine as well.
If your car need replacement parts, take a look at our car accessories for sale. If your car problems are consistent despite repairs, find a suitable and affordable replacement from our collection of used cars for sale in Dubai.
Stay tuned to the UAE’s leading auto blogs for more information on car parts, market trends and auto-technology.