a thermostat is a specific device that maintains a certain amount of heat.The thermostat maintains a constant temperature of the coolant that fills the thermostat. The studied body is in contact with the heat carrier and has its temperature.The General structure of this part includes the main valve, body, cylinder with wax, spring and small circle valve. In its manufacture, copper and brass are used. The idea of working lies in the cylinder, located on the side facing the engine.Variations of this device are also different: 1) 2-valve, the Principle of its operation, is the effect of the internal filler of the thermostat on the bayonet, which in turn opens and closes the path of the coolant. 2) 1-valve device does not have a small circle opening. This type is most often found on models of the foreign car market. It is installed between the lower radiator tank and the pump.3) the Circuit of some motors gives a sufficiently strong pressure that prevents opening.