Some forklifts may experience abnormal engine water temperature after several years of use. After starting the cold car, the water temperature quickly rises and boils within a short period of time, and only returns to normal after adding cooling water. The cooling system of a forklift is relatively simple in structure, generally consisting of components such as a radiator, cooling fan, and thermostat. Cooling fans are often directly driven by the engine, and the fan speed is consistent with the engine speed. The control of cooling water temperature mainly relies on the thermostat. The characteristics of this structure are low cost and easy maintenance, but the drawback is that it is not sensitive to the control of cooling water temperature. The temperature of the engine water is mainly related to whether the thermostat is working properly, whether the water pump can establish sufficient pressure, and whether the cooling fan can reach the standard speed. Judging the malfunction of the cooling system should also start with determining whether these components are working properly.
Below, we will provide a detailed explanation and inspection of the four main components: thermostat, water pump, radiator, and cooling fan.
1. Inspection of thermostat
At present, wax type thermostats are mainly used in engines. Its main performance indicator is that the thermostat should have different lift at different water temperatures. Thus dynamically controlling the temperature of the cooling water. For checking the quality of the thermostat without disassembling the cooling system, it is mainly determined by the temperature difference between the inlet and outlet pipes of the radiator. During the initial period of engine cold start, there should be a noticeable temperature difference between the inlet and outlet pipes when touched by hand. After working for a period of time, the temperature difference significantly decreases. When the engine reaches normal operating temperature (80 ℃ -90 ℃), there is no noticeable temperature difference when touched by hand. The most accurate detection method is to remove the thermostat, place it in hot water, gradually heat it up, and check the opening temperature and lift of the valve.
2. Inspection of water pump
The sufficient pressure of the water pump is the key to the normal operation of the cooling system. When adding cooling water, if the coolant level drops significantly with the increase of engine speed, it indicates that the water pump is working properly. On the contrary, it is possible that the water pump and impeller are loose, and the cooling water cannot circulate. In domestic forklift engines, the water pump, generator, and cooling fan share a belt, so the tightness of the belt directly affects the speed of the water pump, fan, and generator.
3. Radiator
The radiator of a forklift is placed at the rear of the vehicle. Due to the low chassis and poor working environment of the forklift, some debris and dust can easily accumulate on the surface of the radiator, which will seriously affect the heat dissipation effect. After completing daily homework, the surface of the radiator should be carefully cleaned to avoid using high-pressure water guns. Because the pipe wall of the radiator is very thin, if the cleaning pressure is too high, it is easy to cause the radiator to collapse and affect the circulation effect. At the same time, it is strictly prohibited to use "hard water" for cooling water to prevent the formation of scale in the radiator, which may lead to insufficient addition of cooling water.
4. Cooling fan
The detection of cooling fan airflow can be done by placing a thin paper in front of the radiator. When the engine is running, if the paper can be blown open, it indicates that the airflow is sufficient. This is different from the front engine car fan that draws air inward. The blades should not be installed backwards, and the fan cover should be complete and effective.
After checking and determining that there are no obvious faults in the main components mentioned above, other component issues should be considered. For example, whether there is excessive carbon buildup in the combustion chamber, whether the diesel engine injects fuel too early or too late, whether the cylinder gasket is burned out, or whether there are cracks in the cylinder block and cylinder liner. In short, there are various faults in the engine cooling system. As long as the system structure is clear and the root cause of the fault is identified, the problem can be easily solved.
