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2. Cause of failure 1 The pump loses its function as a pump. When the weather is cold, there is no depletion of a small amount of cooling water left in the pump body. Overnight, the water between the impeller and the inner wall of the water pump body may swell and cause the impeller to rotate. After the diesel engine starts running, there is no circulation of cooling water in the cooling water passage, so that the temperature of the body quickly rises, and the water tank “opens the potâ€. In addition, the pins of the fixed impeller are broken or loose, the water pump shaft rotates and the impeller does not move, the water pump stops pumping, the cooling water does not circulate, and the water temperature is too high. 2 The amount of water in the cooling system is insufficient. Before the start of the diesel engine, there is no sufficient cooling water in the tank, or the cooling system leaks, the pump water supply is insufficient, or water channels, heat pipes are blocked by scale and dirt, etc., all cause cooling water shortage. 3 The fan belt slips, breaks, or the blades in the fan are twisted. In this case, the fan belt is too loose and slippery, which reduces the speed of the water pump and causes the cooling water temperature to be too high. 4 The clearance between the cylinder and the piston is too small. The gap between the cylinder sleeve and the piston is too small, the gap between the piston ring cut is too small, the piston rod group is not installed correctly, and the cylinder sleeve is not properly lubricated, which will cause the friction between the piston group and the cylinder sleeve to intensify, which will increase the operating temperature and cause the cooling water to overheat. high. 5 thermostat failure. If the thermostat breaks down, when the water temperature is higher than 70°C, the valve cannot be opened or the height of the valve is not high enough, so that the cooling water cannot pass through the radiator for large circulation and the water temperature is too high. 6 The fuel supply is too late. The fuel supply was too late and the diesel fuel was incomplete, causing the diesel engine to overheat, and the temperature at the bottom of the cylinder head increased, resulting in an excessively high water temperature.
3. Check judgment 1 Check the pump. Hold the cylinder head tightly to connect the water outlet pipe of the radiator, and increase it from idle speed to high speed. If you feel that the water flow increases, it means that the water pump is normal. Otherwise, it indicates that the water pressure of the water pump is not enough and should be checked. If the pin breaks or looses, the pump shaft rotates and the impeller does not move, the pump stops pumping. At this time, the pump impeller pin should be replaced; if the pump impeller is installed in reverse, the pump cannot pump water. 2 Check the cooling water. Check whether the cooling water is sufficient before starting the diesel engine. Check whether the water pipes and heat pipes are blocked. 3 Check the fan belt. If the belt is too loose, it should be adjusted; if the belt is worn or broken, it should be replaced in time; if there are two belts, only one of them is damaged, two new belts must be replaced, and the new belt must not be worn out. Otherwise, This will greatly shorten the service life of the new belt. 4 Check cylinder sleeve and piston clearance. Check if the piston ring notch clearance is too small, and if the cylinder sleeve lubricant is sufficient, replace the relevant parts if not required. 5 Check the thermostat. For engines equipped with a thermostat, if there is a large flow of water out of the inlet pipe of the water tank in the tank, it means that the thermostatic valve is not closed tightly or damaged; if the water temperature exceeds 70°C, the water inlet pipe of the upper water room flows out without water The outflow of large stocks indicates that the thermostat is damaged or weakened. 6 Check if the fuel supply advance angle is normal.
1. Symptoms The temperature of the cooling water is too high. The pointer of the water temperature meter often refers to the temperature above 100°C, and it is accompanied by a phenomenon that the radiator “opens the potâ€. However, due to the self-flow evaporative cooling of the single-cylinder diesel engine such as the S195, water boiling is normal.