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. GOLF VI (5K1)
2. SCIROCCO (137, 138)
3. GOLF V (1K1)
4. RABBIT V (1K1)
5. JETTA III (1K2)
6. JETTA I Saloon (1K2)
7. JETTA V (1K2)
8. BORA V (1K2)
9. VENTO III (1K2)
10. PASSAT (3C2)
11. PASSAT Saloon (3C2)
12. PASSAT / Magotan (3C2)
13. PASSAT Variant (3C5)
14. PASSAT Estate (3C5)
15. A6 (4F2, C6)
16. A6 Saloon (4F2, C6)
17. A6 / S6 (4F2, C6)
18. A6 Avant (4F5, C6)
19. GOLF V Variant (1K5)
20. JETTA V Variant (1K5)
21. See more in applications

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.