What Are The Symptoms Of A Broken Car Thermostat?

If a thermostat cannot be opened, the thermometer will show that the water temperature is in the high temperature area, but the fan in the water tank does not turn, the engine temperature is high, and the antifreeze is easy to be lacking.

If the automobile thermostat is not closed, the water temperature will rise slowly, especially in winter, when the water temperature is still in the low temperature zone for 10-20 minutes, the idling speed will be high.

Thermostat is an automatic temperature-regulating device, which usually contains temperature-sensing components. It opens and turns off the flow of coolant by expanding or contracting. That is to say, it automatically adjusts the amount of water entering the radiator according to the temperature of the coolant and changes the circulating range of the coolant in order to regulate the cooling capacity of the cooling system.

At present, the main thermostat used is the wax thermostat, which is controlled by the internal paraffin through the principle of thermal expansion and contraction. When the cooling temperature is lower than the prescribed value, the refined paraffin in the thermostat temperature sensor body is solid, the thermostat valve closes the passage between the engine and the radiator under the action of the spring, and the coolant returns to the engine through the pump for small circulation in the engine. When the coolant temperature reaches the prescribed value, the paraffin begins to melt and gradually becomes liquid. The volume of the paraffin increases and the rubber tube is compressed to shrink. While the rubber tube shrinks, it pushes the push rod upward, and the push rod pushes the valve backward to open the valve. At this time, the coolant flows back to the engine through the radiator and the thermostat valve, and then through the pump for large circulation. Most of the thermostats are arranged in the outlet pipe of the cylinder head, which has the advantages of simple structure and easy discharge of air bubbles in the cooling system. The disadvantage is that the thermostats are often open and closed when they are working, resulting in oscillation.

When the engine working temperature is low (below 70 degree C), the thermostat automatically closes the access to the radiator, and opens the access to the pump. The cooling water from the water jacket enters the pump directly through the hose, and is fed into the water jacket through the pump for recycling. Because the cooling water does not radiate from the radiator, the engine working temperature can rise rapidly. This circulation route is called small circulation. When the working temperature of the engine is high (above 80 degree C), the thermostat automatically closes the passage to the pump, and opens the passage to the radiator. The cooling water from the water jacket is radiated by the radiator and then sent into the water jacket by the water pump, which improves the cooling intensity to prevent the engine from overheating. This circulation route is called large cycle. When the working temperature of the engine is between 70 80 C, large and small cycles coexist, that is, part of the cooling water circulates in large cycles while the other part of the cooling water circulates in small cycles.

The function of automobile thermostat is to shut down before the temperature of the car has reached the normal temperature. At this time, the cooling fluid of the engine returns to the engine through the water pump and circulates in the engine to make the engine warm up quickly. When the temperature exceeds normal, the cooling fluid can be opened and circulated through the whole radiator circuit of the water tank, so as to quickly dissipate heat.