The high water temperature of diesel generator set is mainly caused by the following reasons:
First, the pump loses its pumping effect. When the weather is cold, the cooling water left in the pump body is not exhausted. The water between the impeller and the inner wall of the pump body may freeze and expand, so that the impeller cannot rotate. After the diesel engine is started, there is no cooling water circulation in the cooling water channel, so that the temperature of the body rises quickly and the water tank is “opened”. In addition, the pin of the fixed impeller is broken or loosened, the water pump shaft rotates and the impeller does not move, the water pump stops pumping water, the cooling water does not circulate, and the water temperature is too high.
Second, the amount of water in the cooling system is insufficient. Before the diesel engine starts, there is no sufficient cooling water in the water tank, or the cooling system leaks, the water supply of the pump is insufficient, or the water pipe and the heat pipe are blocked by scale and dirt, which will cause insufficient cooling water.
Third, the fan belt slips or breaks, or the blades in the fan are twisted. In this case, the fan belt is too loose and easy to slip, causing the speed of the water pump to decrease, resulting in the cooling system water temperature is too high.
Fourth, the clearance between the cylinder and the piston is too small. The clearance between the cylinder liner and the piston is too small, the gap between the piston ring is too small, the piston connecting rod group is not installed properly, and the cylinder sleeve is poorly lubricated, which will cause the friction between the piston group and the cylinder liner to increase, causing the working temperature to rise, resulting in the cooling water temperature is high.
Fifth, the thermostat failed. If the thermostat breaks and fails, when the water temperature is higher than 70°C, the valve cannot be opened or the opening height is not enough, so that the cooling water cannot be circulated through the radiator and the water temperature is too high.
Sixth, the oil supply time is too late. The oil supply is too late, the diesel combustion is not complete, causing the diesel engine to overheat and the temperature of the bottom surface of the cylinder head to rise, resulting in excessive water temperature.
Fault check judgement:
First, check the water pump. Hold the outlet pipe of the cylinder head connected to the radiator by hand. The idle speed is increased to the high speed. If the water flow is increased, the pump is normal. Otherwise, the pump pump water pressure is insufficient and should be dismantled. If the pin is broken or loose, the pump shaft rotates and the impeller does not move, the pump stops pumping water. At this time, the pump impeller pin should be replaced; if the pump impeller is installed in reverse, the pump cannot pump water.
Second, check the cooling water. Check if the cooling water is sufficient and check if the water pipe and heat pipe are blocked before starting the diesel generator.
Third, check the fan belt. If the belt is too loose, it should be adjusted; if the belt is worn too much or broken, it should be replaced in time; if there are two belts, only one of them is damaged, must be replaced with two new belts, and it should not be used together with one old and one new. Otherwise, it will greatly shorten the service life of the new belt.
Fourth, check the clearance between the cylinder liner and the piston. Check if the clearance of the piston ring is too small, and whether the cylinder liner lubricant is sufficient. If it does not meet the requirements, replace the relevant parts.
Fifth, check the thermostat. The engine is equipped with a thermostat, if there is a large amount of water flowing out from the water inlet pipe of the water chamber of the water tank, it means that the thermostat valve is not tightly closed or damaged; if the water temperature greatly exceeds 70°C, the water inlet pipe of the upper water chamber does not flow out or no large amount water flows out, indicating that the thermostat is damaged or weakened.
Sixth, check if the fuel supply advance angle is normal. Note: When the fuel injection advance angle is not normal, the exhaust smoke color of the diesel generator set will also be abnormal.
It may also be caused by the following reasons:
The radiator surface of the cooling water tank is not clean. Mainly due to the dusty environment, it is easy to block the surface of the radiator or when the generator set is running, debris is sucked by the cooling fan to the water tank to block the ventilation and make the heat dissipation poor. Clean the radiator surface with water or remove debris. Therefore, daily attention must be paid to keep the environment in the equipment room clean.
The use of undesirable coolant causes the cooling water pipe to accumulate scale, rust, etc., which hinders the circulation of the cooling water and causes the water temperature to rise. For the use of coolant, we must use at least qualified tap water, preferably distilled water, deionized water or pure water.