Thermostat is a device for maintaining a static (constant) temperature, as its name implies. There are thermostats of different designs in many devices and mechanisms, from water heaters to refrigerators. There is also a thermostat in a car's internal combustion engine (liquid-cooled, of course). In a car, the thermostat regulates the temperature of the coolant (antifreeze): it accelerates the warm-up of a cold engine and provides heat removal from the hot one. Therefore, the engine works more efficiently and more comfortably for the driver, especially in winter - without a thermostat, the stove would usually blew cold air.

1. 3 (E30)
2. 3 Saloon (E30)
3. 3 Touring (E30)
4. 3 (E36)
5. 3 Saloon (E36)
6. 3 Coupe (E36)
7. 5 (E34)
8. 5 Saloon (E34)
9. 5 Touring (E34)
10. 3 Convertible (E30)
11. 3 Convertible (E36)
12. 5 Touring (E39)
13. Z3 Coupe (E36)
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The principle of the thermostat work

The classic MEYLE brand Thermostat, coolant is a movable valve that moves due to a change in the external environment - heating or cooling of antifreeze. The thermostat is made of a thermoelement filled with a substance resembling wax in structure - ceresin, with the addition of copper powder, graphite or aluminum for better thermal conductivity. At a certain temperature of the antifreeze, ceresin expands, opening the thermostat valve. When the motor cools down, ceresin contracts and the thermostat closes again.