Engine Cooling System (For Car)


A thermostat is a part of an engine cooling system. The thermostat helps to maintain the engine coolant temperature within the normal operating range.
How it works:
When the engine started cold, the thermostat is closed. The engine coolant (antifreeze) does not circulate through the radiator (see the pictures). Instead it returns back into the engine through the by-pass tube. This helps to warm up the engine faster.
As soon as the engine temperature reaches the normal range, the thermostat opens and the engine coolant starts circulating through the radiator where it cools down.
If the coolant temperature in the radiator drops too low, for example when driving on a freeway in a cold weather, the thermostat closes again to keep the temperature within operating range.

Thermostat problems:
Thermostat problems are common. Defective thermostat must be replaced - luckily, it's fairly inexpensive part.

Thermostat stuck open

The thermostat is closed when the engine is cold

If the thermostat does not close properly or stuck open, it will take a long time for a car engine to warm up. Also when driving in cold weather, especially on a freeway, the engine temperature might drop below normal range causing the heater not to work properly.

Thermostat stuck closed

The thermostat is open when the engine is warmed up

If the thermostat stuck closed or does not open fully, the engine might overheat which may cause serious damage to the engine.