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. 240 (P242, P244)
2. 240 Saloon (P242, P244)
3. 240 Kombi (P245)
4. 240 Break (P245)
5. 240 Rural (P245)
6. 340-360 (343, 345)
7. 740 (744)
8. 740 Saloon (744)
9. 740 Kombi (745)
10. 740 Break (745)
11. 740 Estate/Combi (745)
12. 740 Rural (745)
13. 760 (704, 764)
14. 760 Saloon (704, 764)
15. 340-360 Saloon (344)
16. 940 (944)
17. 940 Saloon (944)
18. 940 Kombi (945)
19. 940 Break (945)
20. 911 Convertible (964)
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The principle of the thermostat work

The classic VALEO 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.