There is a common practice of removing your car’s thermostat valve in Pakistan if it starts showing signs of overheating every now and then, especially in small three cylinder cars. The drivers believe that removing the thermostat will cure any overheating issues of the car. The job of the thermostat is the keep the engine at its optimum temperatures by managing the flow of coolant from radiator to engine block and then back to radiator. Its job is to block the flow of coolant to the radiator until the engine has warmed up. When the engine is cold, no coolant flows through the engine. And once the coolant temperature starts to rise, from engine’s normal operating temperature, the thermostat will open to let the fresh coolant from the radiator inside the engine block. Simply put, it stops the fresh coolant from reaching engine so that engine reaches its operating temperature quickly and then opens up to let the coolant from the radiator to the engine block when temperature of the coolant inside the engine block starts to increase.
The mechanics of the thermostat are simple, sort of. There is small capsule on the engine side of the thermostat that is filled with wax that expands or contracts depending upon the temperature of the coolant. There is this small pin pressing into the wax. Around that pin is a spring that stops the valve from opening. The wax melts inside the capsule with increase in temperature, as a result, it expands and pushes the pin out. Pin is held inside a bracket attached to the body of the valve, at the other end of it. It pushes against the bracket and opens the valve to let the coolant in. Simple, eh?!
Removing the thermostat from your car, big or small, is not a good idea. Instead of actually finding the reason why their cars are overheating, people usually choose a shortcut and just throw the thermostat valve out. Overheating could be something as simple as your thermostat valve being stuck closed or your radiator being clogged or even air in the cooling system. In severe cases, it could be because of reasons like a blown head gasket or worse, your cylinder head might have gone kaput.
Removing your thermostat will prevent your engine to reach its optimum operating temperatures. Engines are designed to work at their max potential when they are all warm and toasty. Optimum operating level means your engine oil being at its best viscosity, your engine hardware at its best temperature so it generates less friction, your charge (mixture of air and fuel) being ignited at the best temperature to extract as much bang from it as possible (otherwise you’ll get bad fuel average from your car), and a host of other things. Running your engine without a thermostat will, for a lack of better word, ‘over-cool’ your engine, and that is big no. This can seriously harm your engine and reduce its life by increase in premature wear and tear of its components. Trust me, I know. I have personally killed an engine like that.
Have your engine pressure tested from a good mechanic/workshop if it’s overheating and keep that small yet very significant part of your engine where it belongs… inside the engine!