Common Fault Diagnosis and Removal of Cooling System

The main fault of the cooling system is that the temperature of the engine is too high, which is mainly divided into three situations: the cooling water is sufficient but the temperature is too high, the cooling water is insufficient and the temperature is too high, and the temperature is suddenly too high during work.

1. The engine temperature is too high

（1）The cooling water is sufficient but the temperature is too high

① Phenomenon The engine cooling water meets the standard and there is no water leakage, but the power is insufficient during operation, and the water temperature exceeds 90°C or even boils (commonly known as boiling).

②The reason is that the fan belt is too loose or slips; the large circulation of the thermostat or the water distribution pipe is not working well, the radiator outlet pipe is shrunk or the pipe wall is delaminated and blocked; the radiator fins are dumped too much or the water pipe is blocked; the fan blade is deformed, the angle Improper, excessive scale deposits in the water jacket of the cylinder block, and other reasons, such as too late ignition time, too rich or too lean, etc.

③Diagnosis and troubleshooting First check whether the fan blades are deformed, and whether the belt is too loose or slipping. If it is good, then check whether the water circulation system is normal, whether the rubber hose is sucked, whether the pipe wall is delaminated, whether the thermostat is invalid, whether the radiator is blocked, whether the blades are dumped too much, whether the scale of the cylinder is too much, and whether the water distribution pipe is not. damaged or blocked. If it is still overheated after inspection, the reasons for technical use should be considered.

（2）The cooling water is insufficient and the temperature is too high

① Phenomenon The engine cooling system cannot accommodate the specified amount of cooling water; the cooling water consumption is abnormal during operation.

②The reason is that the radiator has too much scale, partial blockage, water leakage or failure of the intake and exhaust valves, and the engine water pump leaks; the cooling water is not drained and frozen in winter, and the cylinder bore communicates with the cylinder; the valve chamber wall is broken and leaked, and other parts of the cooling system leak water.

③Diagnosis and elimination First, check whether the cooling water capacity is sufficient, whether the radiator is in good condition, and whether there is water leakage in each part of the cooling system. In winter, pay attention to check whether the radiator is frozen and whether the water pump is leaking. If there is no water leakage outside the cooling system, but the cooling water consumption is still relatively fast, consider whether there is water leakage inside the cooling system. Bad communication with the cylinder. At the same time, check whether the exhaust valve of the radiator fails.

（3）The engine suddenly overheats

① Phenomenon The pointer of the water temperature gauge quickly indicates the position of 10C; the engine power drops significantly: when the cold car is started, the water temperature rises rapidly and boils, and it becomes normal after supplementing the cooling water.

②Causes: The fan belt is broken or the fixed fulcrum of the generator is loose or displaced; the main valve of the thermostat falls off; the water pump shaft and the impeller are loose, and the cooling system leaks seriously; the cylinder gasket is damaged, the water pump communicates with the cylinder, and the high-pressure airflow enters the waterway.

③Diagnosis and elimination If the engine suddenly overheats during operation, you should pay attention to the dynamic of the ammeter. If the engine speed is increased, the ammeter shows no charging or the charging indicator light is on, indicating that the fan belt is broken and the water pump does not work. If you touch the radiator and engine by hand and find that the temperature of the engine is high and the temperature of the radiator is low, it means that the water pump shaft and the blades are loose. If the temperature rises rapidly and the cooling water boils when the cold car is started, it is mostly because the main valve of the thermostat falls off. Check the cylinder head gasket for damage if necessary.

2. Engine temperature is too low

① Phenomenon The indicated value of the thermometer is lower than the normal working temperature of the engine, the engine is weak, and the muffler has a blasting sound; the fuel consumption increases.

②The reason is that thermal insulation facilities are not used in severe cold areas; the thermostat fails; the engine lubricating oil is too much.

③Diagnosis and troubleshooting Check the amount of engine lubricating oil, if it is too much, it should be released, keep an appropriate amount of lubricating oil, and then check whether the thermostat fails, if it fails, it should be replaced.