The thermostat is a key component of the cooling system in an internal combustion engine that regulates the flow of coolant to keep the engine within the proper operating temperature range. It works automatically, opening and closing depending on the coolant temperature.

How does a thermostat work?

Closed state (cold engine) :

• When the engine is cold, the thermostat remains closed. This causes the coolant to circulate only inside the engine, bypassing the radiator.
• This allows the engine to reach operating temperature faster, which is important for its performance and protection against wear.

Open state (hot engine) :

• When the engine reaches a certain temperature (usually between 80°C and 95°C, depending on the vehicle model), the thermostat opens. This allows the coolant to flow into the radiator, where it is cooled before being returned to the engine.
• The thermostat opens gradually as the temperature rises to ensure optimal flow and cooling.

Thermostat construction:

The thermostat contains a thermosensitive element, often in the form of a capsule filled with wax. The wax expands when heated, causing the valve to open. When the temperature drops, the wax contracts and the thermostat closes.

Importance of thermostat:

• Optimum operating temperature : The thermostat helps keep the engine in its optimal temperature range, which reduces fuel consumption and emissions, and prevents the engine from overheating.
• Engine protection : Too low a temperature can cause insufficient engine lubrication, while too high a temperature can cause thermal damage.