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. 1 (F20)
2. 6 Coupe (F13)
3. 5 (F10)
4. 5 Touring (F11)
5. X3 (F25)
6. X3 SAV (F25)
7. 3 Touring (E91)
8. 6 Convertible (F12)
9. 3 (F30, F80)
10. X5 (F15, F85)
11. X5 SAV (F15, F85)
12. 3 (E90)
13. 3 Saloon (E90)
14. X1 (E84)
15. X1 SAV (E84)
16. X1 SUV (E84)
17. 3 Coupe (E92)
18. 3 Convertible (E93)
19. 5 Gran Turismo (F07)
20. 4 Coupe (F32, F82)
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The principle of the thermostat work

The classic FEBI BILSTEIN 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.