When the water temperature is high, it could just be a stuck thermostat

In the hot summer season, many drivers have encountered the problem of engine overheating. In addition to common causes such as radiator blockage due to foreign objects or damaged fan clutches, there is another small component on our engine that should not be overlooked, and that is the thermostat.

The thermostat functions by automatically regulating the volume of coolant entering the radiator based on its temperature, thereby adjusting the cooling power of the engine's cooling system to maintain the engine temperature within an optimal operating range. In simple terms, it is a small component that helps maintain a relatively constant coolant temperature in the engine. Its proper functioning directly affects the temperature of our engine.

When the thermostat is functioning properly, it is normal for the coolant temperature to increase to some extent during engine operation under heavy loads, such as climbing steep inclines. However, once on level ground, the coolant temperature should quickly return to normal. However, some drivers may experience a different situation where the coolant temperature remains normal during light loads on level ground but rises significantly under slight additional load. It may also take a longer time for the temperature to decrease back to normal after returning to level ground.

When you touch the upper and lower water pipes of the radiator and both feel warm, it can easily lead to misjudgments about potential malfunctions. One might mistakenly think that the fan clutch is faulty or the radiator is blocked, and even after cleaning and replacing parts, the issue persists. In such cases, it's possible that the thermostat is stuck, causing this problem. Therefore, when your vehicle exhibits the symptoms described above, it's worth considering checking the thermostat.

The checking method is also simple: remove the thermostat from the vehicle and place it in a pot to boil. Observe whether the thermostat opens as the water temperature rises and whether there is any sticking during the process. If your vehicle's thermostat is controlled by skirt movement to regulate the small circulation, as seen in engines like the Dongfeng dCi, apart from checking for thermostat sticking, you also need to inspect if any foreign objects have caused the water pump housing to jam.

It's not easy for us truck drivers. After all, a vehicle is made up of numerous components, and it's inevitable that some issues may arise. However, when we encounter problems, we shouldn't blindly replace parts. Instead, we should identify the root cause and apply the appropriate solution. We need to address the issue in a cost-effective way to truly solve the problem.