Fault phenomenon: a customer reported that the engine water temperature is high, which is also a common fault, so what is the cause? Let's have a detailed analysis below!
Fault analysis: start the vehicle, connect ISID for quick test, and check whether there is no relevant fault code of radiator element with high water temperature. Activate the electronic fan with the computer, the fan turns at high speed, indicating that the electronic fan is normal. The test drive lasted for more than ten kilometers, and the vehicle was put into normal working condition temperature. Connecting ISID to check the engine data, it was found that the engine coolant temperature slowly increased to 120 degrees, while the water tank outlet temperature slowly decreased from 50 degrees to 33 degrees, which was abnormal. Try to touch the upper water pipe and the lower water pipe of the water tank. It is found that the temperature difference is great, the upper water pipe is extremely hot, and the lower water pipe is normal. At this time, the electronic fan does not turn.
At this time, it is judged that there are several possible problems:
1. The thermostat does not open and cannot complete the large cycle.
2. The water pump is damaged and cannot circulate the water.
3. The water tank is blocked and the water cannot be circulated.
4. The engine water channel is blocked or the air channel may be the same as the water channel. The air is blocked and the water cycle cannot be completed.
Fault result: it is doubted that the problem is the thermostat. However, observe the water flow of the car. When the water from the water pump passes through the thermostat after it is connected, it does not go through the upper water pipe, but through the empty water, which enters into the lower water pipe of the water tank, resulting in the cooling cycle fracture in the engine, temperature difference between the upper and lower water pipes, and no water flow in the upper water pipe. After replacing the new thermostat, the temperature value of the engine is normal, and it is also normal after starting in situ for several hours, and there is no high temperature phenomenon in the test run.