The overheating phenomenon caused by the serious leakage of the engine due to the lack of coolant can be directly diagnosed through observation, and the trouble can be eliminated smoothly. When the engine is running, the phenomenon that the engine is overheated because of excessive cooling water consumption should first fill the radiator with water, run the engine at idle speed, check whether there are leakage phenomena in the radiator, water pump hole and the cooling system, if it should be excluded. Check whether there is water in the crankcase oil, if the water content in the engine should be disassembled and overhauled. Check if there is a drainage phenomenon in the exhaust pipe. If possible, it may be the cylinder gasket is damaged, so that the water jacket is in collusion with the cylinder. Therefore, the cylinder cushion should be repaired and replaced. There are 2 reasons for the overheating of the engine due to the capacity of the cooling system below the standard capacity: first, too much scale. With the increase of the mileage, the scale of the water jacket wall and the cooling pipe will be thickened gradually with the increase of the mileage, especially the high temperature part, which seriously affects the heat dissipation effect of the radiator. The heat generated by engine work is difficult to disperse in time and overheat. For excessive scale, scale cleaning agent can be selected, and scale can be removed according to the operation method. The two is that the radiator is blocked by the sundries. There are many impurities in the radiator, such as oil sludge, scale and cotton yarn, which block many core pipes, making the actual capacity of the radiator much lower than the standard capacity. When the impurities in the engine are removed, the overheating phenomenon will disappear. If the indicating discharge or charging indicator lights are on the way and the engine is overheated, the pump belt should be broken. If the water pump belt technology is in good condition and the tension is suitable, the failure of the pump can be considered, causing the engine to overheat due to the interruption of the cooling water cycle. At this point, touch can be used to diagnose. The specific symptoms are the high temperature of the engine, especially the lower part of the radiator. In this regard, the pump should be overhauled or replaced.