The function of the engine cooling system is to send the heat from the high temperature parts of the engine to the atmosphere in time to keep the engine at the most suitable temperature. When the engine works, the fan and the water pump rotate, and the cooling water comes into the cylinder head and water jacket by the water pump under the action of the water pump. After the heat absorption, the water pipe of the cylinder cover and the thermostat enter the upper part of the radiator, and then flow through the radiator core to the lower part of the radiator. In this process, the heat is passed to the radiator core and heat dissipation. A piece of piece. At the same time, due to the rotation of the fan, the air is blown away from the radiator, and the heat is taken away to reduce the temperature of the cooling water, and the water is repressed into the water jacket by the water pump. In this way, the temperature of the cooling water can be kept within 80~90 degrees, no matter what the engine works. If the engine cooling system fails, the function of the cooling system can not be fully brought into play, which will cause the engine to overheat during the operation, resulting in the engine power decline and the damage of the engine parts. The common fault causes and maintenance methods of the engine cooling system are described below for reference to drivers and maintenance personnel of agricultural vehicles. The cooling system is a fully sealed system. Only when the cooling system fails, can it cause leakage of coolant. Therefore, in normal use, there is no need to add coolant frequently. It takes time to add coolant. If the coolant consumption is too fast, it indicates that the cooling system has failed and the coolant has leaked. The cause of the trouble should be found in time, and the trouble should be eliminated to ensure the normal operation of the cooling system. 1. cause of failure (1) radiator crack or perforation leakage. The water jacket of the cylinder body is damaged and the cooling water is lost. (2) the breakage and leakage of the inlet and outlet pipes. (3) the switch damaged the leakage. 2. troubleshooting method (1) uses leak stopping agent to stop leakage. If there is serious leakage, radiator should be replaced. (2) if the water pipe is cracked and aging, new parts should be replaced. (3) switch should be replaced if the coolant leakage is caused by the switch damage. 1. reasons for failure (1) the cooling water is not enough. (2) the fan transmission belt is broken or adjusted too loose, and the cooling effect will disappear or weaken. (3) the scale of the water jacket and radiator of the cylinder block is more, and the heat dissipation performance is reduced. (4) the pump is not working properly, and the water circulation is not smooth. (5) radiator fins toppling or connecting hose suction. (6) the water temperature meter and the sensor fail. 2. troubleshooting method (1) timely add cooling water, if the radiator leakage should be repaired. (2) adjust the tightness of the fan belt or replace the new transmission belt. (3) cleaning the cooling system and removing scale. (4) to repair or replace the water pump. (5) check the outlet pipe, such as suction should be eliminated, repair radiator radiator. (6) overhaul or replace the water temperature meter and sensor. 1. in driving, if the temperature of the coolant is below the normal temperature of the engine (75 degrees C), or the temperature of the coolant temperature meter of the engine can not reach the normal position for a long time, it shows that the working temperature of the engine is too low or the temperature is slow. The low working temperature of the engine will make (1) the combustible mixture temperature of the entry cylinder is too low, making the ignition difficult or the burning delay, causing the fuel consumption to increase, and the engine can not produce the due power. (2) the increase of lubricating oil makes the engine lubrication bad, aggravating the wear of parts, and increasing power consumption. (3) because of the low temperature and non atomized fuel, the erosion of the oil film on the friction surface and the dilution of the lubricating oil aggravate the wear of the parts. 2. cause of failure (1) coolant thermometer or coolant temperature sensor damage, indicating an error. (2) thermostat leakage or valve sticking can not be closed. (3) the fan clutch or temperature control switch is too early. 3. troubleshooting method (1) check whether the shutters are closed and take effective thermal insulation measures when the ambient temperature is low. (2) check whether the fan control device is invalid. If the cooling system is equipped with a fan clutch or an electric fan, the failure of the fan control device can be determined by observing the operating state of the fan when the working temperature of the engine is low. (3) check whether the thermostat is normal. When the engine working temperature is low, the temperature of the first test radiator is used to judge whether the coolant is in large circulation to diagnose whether the thermostat is normal. When water meets oxygen in iron and air, it acts as a chemical and becomes rust. The water jacket of the cylinder is made of alloy aluminum and pig iron. There is no need for bubbles in the water, so the metal parts in the cooling system are gradually rusted, and even can not be used. Generally, rust is 90% of the solid plugging water jacket in the radiator. The result of rust accumulated over time can almost fill the water jacket, which has great influence on the engine cooling system. 1. cause of rust in water jacket (1) air in water jacket. (2) the temperature of the water is raised. The increase of water temperature can also accelerate the corrosion. (3) water contains mineral salts and other minerals, which can accelerate metal corrosion in water jacket. 2. method of troubleshooting (1) check whether the water surface of the radiator is too low, if it is too low to add cooling water to ensure the water surface height of the water tank to prevent the air from entering the water jacket. (2) in the engine work, we must keep the cooling system working normally and prevent the cooling water from being too high. (3) when adding cooling water to the water tank, clean soft water should be added. The river or well water can not be added directly. In addition, anti rust agent can also be added. Its function is to prevent rust, but it can not exclude the original rust. The cooling system should be rinsed out before the injection.