What is the function of the thermostat in the water pipe on the car engine?

The thermostat is a valve that controls the flow path of coolant.

The function is to automatically adjust the amount of water entering the radiator according to the temperature of the cooling water, and change the water circulation range to adjust the heat dissipation capacity of the cooling system and ensure that the engine operates within a suitable temperature range. The thermostat must be kept in good technical condition, otherwise it will seriously affect the normal operation of the engine. If the main valve of the thermostat is opened too late, it will cause the engine to overheat; if the main valve is opened too early, the engine warm-up time will be extended and the engine temperature will be too low. At this time, it can be judged whether the working condition of the thermostat is good. When the engine starts to run cold, if there is still cooling water flowing out of the water inlet pipe of the water tank, it means that the main valve of the thermostat cannot be closed; when the engine cools down, When the water temperature exceeds 70 degrees Celsius and there is no cooling water flowing out of the water inlet pipe of the water tank, it means that the main valve of the thermostat cannot open normally, and repair is required.