Water Temperature of Water-cooled Diesel Engine Is Too High

Excessive water temperature is one of the most common failures of diesel water-cooled type. Due to the different thermal expansion coefficients of the cylinder sleeve and piston friction pair material, the high temperature will make the gap smaller, the lubrication condition will deteriorate, and the cylinder and piston ring will be stuck for a long time. In addition, if the water temperature is too high, the viscosity of the lubricating oil will decrease, and the oil film will be destroyed to reduce the lubricating effect and the dynamic performance. Therefore, the diesel engine water temperature must be controlled to the allowable value. There are nine main reasons for the excessive water temperature in diesel engines.

1. Improper use of coolant or insufficient water. The diesel engine used in construction machinery generally has a higher working temperature. The antifreeze can ensure its high boiling point and reduce the scale generated by the cooling system. If the cooling system is not removed, or the coolant is not replenished in time, the cooling performance will be degraded. To raise the temperature of the coolant.

2. The water radiator is blocked. For example, the heat sink of the water radiator has a large area of lodging, and there are oil and mud debris between the heat sinks, which will prevent the heat from being emitted. Especially when the surface of the water radiator is contaminated with organic oil, the thermal conductivity of the sludge mixture formed by the dust and the oil is smaller than that of the scale, which seriously hinders the heat dissipation effect. At this point, use a thin steel sheet to carefully return the heat sink to its original position, restore the flat shape of the heat sink, and then use compressed air or a water gun to clean it. If the water is heated and put into the cleaning solution, sneeze, the effect is better.

3. The water temperature gauge or warning light is incorrectly indicated. Including the water temperature sensor is damaged; the line is ironed or the indicator is out of order, resulting in false alarm. At this time, the surface thermometer can be used to measure the temperature at the water temperature sensor, and it is observed whether the water temperature gauge indicates the actual temperature.

4. The fan speed is too low, the blade is deformed or reversed. If the fan tape is too loose, it will slip, causing the fan speed to be too low and the air supply effect to be weakened. If the tape is too loose, it should be adjusted. If the rubber layer is aged, damaged or the fiber layer is broken, it should be replaced. When the fan blade is deformed, it can be compared with the new blade of the same specification to see if the angle between the blade and the relative rotation plane becomes smaller. If the angle is too small, the air supply strength will be insufficient.

5. The cooling water pump is faulty. The pump itself is damaged, the rotation speed is too low, the scale in the pump body is excessively deposited, and the narrowing of the passage will make the flow rate of the coolant smaller, the heat dissipation performance is lowered, and the temperature of the diesel engine oil is increased.

6. The thermostat is faulty. The function of the thermostat is to control the size cycle of the cooling system. When the thermostat is working at about 85 degrees, the valve starts to open, and the valve is fully opened at about 105 degrees. The method of checking the thermostat is to remove the thermostat, suspend it in a container filled with warm water, and place a thermometer in the water, then heat it from the bottom of the container to observe that the thermostat valve starts to open and If the water temperature is completely turned on, if the above requirements are not met or there is obvious damage, the thermostat should be replaced immediately.

7. The cylinder head gasket is damaged. If the cylinder head is burned by the high temperature gas, the high pressure gas will rush into the cooling system to make the coolant roll and boil. The method of judging whether the cylinder head is burnt is: turning off the diesel engine, waiting for a while, then restarting the diesel engine and increasing the speed. If at this time, the water radiator cap can be seen to have a large number of bubbles emerging, and at the same time, there is a small water droplet in the exhaust pipe discharged with the exhaust gas, it can be concluded that the cylinder head gasket is damaged.

8. Inappropriate fuel injection time. The injector is not working well. If the fuel supply advance angle is too early or delayed, the contact area of the high temperature gas with the cylinder wall increases during combustion, and the time is prolonged, and the heat transferred to the coolant increases, and the temperature of the coolant rises. At this time, there is a phenomenon that the power of the diesel engine is lowered and the fuel consumption is increased. If the fuel injection pressure of the injector drops, the fog will be poor, and the fuel will not be completely burned. The increase of the exhaust temperature will indirectly lead to an increase in the water temperature.

9. The diesel engine is overloaded. When the diesel engine is overloaded, it will cause too much oil supply. When the generated heat exceeds the heat dissipation capacity of the diesel engine, the temperature of the coolant of the diesel engine will also rise. At this time, the diesel engine has more black smoke, increased fuel consumption, and abnormal sound.