Why do more and more engines use double thermostats?

The thermostat controls the temperature of the engine coolant. When the coolant temperature is lower than the operating temperature, the engine coolant flows back through the bypass to the pump inlet. When the engine coolant temperature reaches the operating range, the thermostat opens and closes the bypass. Turn on the big circulation mode, forcing the engine coolant to flow into the radiator for cooling.

More and more heavy-duty diesel engines are now using double thermostats, such as the Xichai 6DL2, Hino E13C, Yuchai, Foton Cummins and other engines. The temperature of the two parallel thermostats of the MAN engine is 83. °C.

The Foton Cummins ISG engine is equipped with two adjustable thermostats. The double thermostat design increases the flow area of ​​the coolant. The increased flow area reduces the pressure of the circulating coolant.

The thermostat opening temperature for the low operating range is 82-95°C, the thermostat opening temperature for the high operating range is 88-97°C, the thermostat temperature is imprinted on the top of the thermostat, and 82°C indicates the low operating range thermostat. , 88°C indicates a high operating range thermostat.

More and more large-displacement engines are starting to be used, and their coolant flow is greater. With double thermostats, both thermostats are turned on at high temperatures, and the cross-sectional area of ​​the coolant flow increases, and the temperature of the water does not rise. Too fast, to enhance the cooling effect, while the reliability of the two thermostats is higher, if one thermostat is broken, it will affect the engine work. The double thermostat is more reliable.

In addition, the double thermostat also has the function of energy saving. For the electronically controlled diesel engine, the water temperature is a very important fuel injection reference signal. The engine itself has a suitable working temperature. It is not good if it is too high or too low. Use double sections. The temperature controller can achieve more accurate water temperature regulation control, which helps to save energy and reduce fuel consumption.

In addition, some vehicles using double thermostats can also achieve separate control of the cylinder head, such as the Volkswagen four-cylinder engine, because the cooling of the engine itself to ensure that the temperature difference between the inlet and outlet can not be too large, double problems can be a good match to meet this demand .

The thermostat has a calibration temperature, which is usually imprinted on the top of the thermostat. This temperature refers to the problem that the thermostat starts to open. The temperature calibration of different thermostats of different engines may not be the same. Even the same type of engine varies according to tuning. Thermostat calibration temperature is not the same.

For a double thermostat engine, it may be that both thermostats have the same temperature, but also have different temperatures, such as the Foton Cummins ISG engine. Therefore, when the thermostat is replaced, it is necessary to check the calibration temperature of the thermostat.

Check the thermostat outside for damage, check for cracks, insert debris, seat damage and other damage. If any damage is found, replace the thermostat. If you suspect that the thermostat has failed, measure the thermostat Turn on the temperature to determine if each thermostat works properly.

Determine each thermostat to measure the corresponding opening and closing value. When installing, ensure that the thermostat and the opening are correctly matched, and a separate positioner on each thermostat ensures that the thermostat will not be loaded in the wrong position .

In addition, some car owners will remove the thermostat. This is a very wrong practice. On the one hand, it will lead to long-term low-temperature engine operation, increased engine wear and premature damage, and will also affect the engine's fuel consumption.