A thermostat is a valve that controls the flow path of coolant. It is an automatic temperature control device, usually containing a temperature sensing component that opens or closes the flow of air, gas, or liquid through expansion or contraction.

The thermostat is used to control the circulation of coolant. When the thermostat is opened, the coolant undergoes a large circulation; When the thermostat is closed, the coolant undergoes a small cycle. So what is' size loop '? There are two circuits for coolant circulation, one passing through the water tank and the other only inside the engine, without passing through the water tank. Everything that passes through the water tank is a major cycle. The coolant comes out of the engine, cools through the water tank, and then returns to the engine. This cycle line is called a major cycle. A cycle without passing through the water tank is a small cycle, and the coolant only circulates internally in the engine without passing through the water tank. The reason why coolant cannot come out is because it is blocked by the thermostat. Once the thermostat is turned off, the coolant cannot come out until it is opened.

Some older cars may experience high summer water temperatures due to the thermostat, so many car owners choose to remove the thermostat to keep the coolant in a high circulation state. But in winter, the ambient temperature is relatively low. When the car lacks a thermostat, the water temperature cannot reach the normal working temperature of the engine, which can lead to low engine temperature and insufficient combustion, accelerating the wear rate of the engine.

When the engine is cold, in order to raise the water temperature as soon as possible, the thermostat is turned off, and the coolant can only circulate inside the engine. When the engine is first ignited, it will also cooperate with the high idle speed of the engine, and the water temperature will rise quickly. When the water temperature is too high, the thermostat will open and pass through the water tank to cool down. After the temperature is too low, the thermostat will close to maintain heat. If there is no thermostat, the external environment temperature is low, and the water tank is constantly dissipating heat, the water temperature will remain very low, which not only harms the engine but also leads to a lack of heating. Therefore, when the thermostat is removed from the car, it needs to be reinstalled before winter approaches.