If the engine water temperature is too high, first analyze the causes.
1. Whether the coolant is sufficient;
2. Whether the thermostat works normally;
3. Whether there is too much scale in the water tank;
4. Check whether the radiator is covered by foreign matters. Then add coolant, thermostat maintenance, clean the water tank or radiator according to the actual situation.
As soon as the May Day holiday is over, the temperature across the country rises rapidly. Driving in hot weather will not only bring a great test to card friends’ health, but also a great test to vehicles. This season is the high incidence season of vehicle failures. Trucks running outside all year round are prone to excessive engine water temperature under high temperature, which is what we often call “boiling pot”.
Under normal circumstances, the water temperature of the engine should be between 80 ℃ – 90 ℃. If the water temperature is often higher than 95 ℃, the water temperature is too high. So, what are the reasons for the high engine water temperature? How should we deal with these problems in daily operation?
The heat of the engine is dissipated through the coolant circulation. If the coolant is insufficient, the heat taken away will naturally be reduced. If you check the coolant and find that the coolant level in the water tank is lower than the minimum scale mark, it indicates that the coolant is missing.
1. Check whether there is water leakage outside the cooling system. If there is water leakage, repair the water leakage position first;
2. If there is no water leakage, add coolant to the specified scale.
When adding coolant, be careful not to open the water tank cover immediately after stopping. At this time, the water temperature in the water tank is very high and the pressure is very high. Opening it immediately may cause high-temperature steam to spray out and scald us. It is recommended to wait for a period of time before opening it. In order to prevent steam from scalding your arms, it is best to put a towel when opening the water tank cover.
The main function of the thermostat is to adjust the cooling intensity of the cooling system. It is prone to failure or function decline after long-term use, resulting in slow or even interruption of water circulation.
As shown in the figure above, when the engine temperature is low, the thermostat will close the large circulating water circuit and connect the small circulating water circuit to reduce heat loss and make the engine temperature rise rapidly. After the engine temperature rises to a certain value, the thermostat will connect the large circulating water circuit and close the small circulating water circuit. After the thermostat fails, the large circulating water circuit cannot be connected, which will cause poor heat dissipation.
Remove the thermostat and put it into hot water:
1. When the water temperature rises to about 70 ℃, the main valve of the thermostat shall start to open;
2. When the water temperature reaches 80-86 ℃, all valves of the thermostat shall be opened, and the valve height shall generally not be less than 9mm.
If the above requirements are not met, the thermostat needs to be repaired or replaced.
When the water tank is not cleaned for a long time or regular antifreeze is not used, the cylinder block and radiator are easy to accumulate thick scale. Due to the poor thermal conductivity of scale, it will lead to poor heat dissipation after blocking the water tank. Therefore, the water tank needs to be cleaned regularly, and pay attention to the use of regular antifreeze.
Chemically clean the cylinder block and radiator with chemical cleaning solution, and replace the water tank if necessary. The thermostat shall be taken out during cleaning. After the cleaning fluid is discharged, the water drain switch shall be removed, the dirt shall be removed, and then the engine water jacket and radiator shall be washed with clean water.
After the heat sink is covered and blocked by oil sludge, leaves and other sundries, the air inlet volume and heat exchange capacity will be greatly reduced, resulting in too high water temperature. In the season when willow catkins float, a large number of willow catkins will be attached to the heat sink. After the heat sink is covered with a layer of “quilt”, the heat dissipation effect is not ideal.
1. After the engine is shut down, blow it with compressed air from behind the radiator or flush it with low-pressure water flow. The reason why the high-pressure water gun cannot be used for flushing is that it will cause damage to the radiator;
2. Clean the core with a soft brush after removing sundries.
After the water tank boils, if the boiler is driven at high speed, you can’t stop and turn off the engine immediately. Instead, you should pull over and idle for a while before turning off the engine, and open the engine compartment cover to let the engine dissipate heat.
Why not stop the engine immediately? Because the engine is running at a high speed when boiling, the large amount of heat generated by the engine also needs residual cooling water to dissipate the heat. If the engine stops running, the heat dissipation system will not work, and the high temperature will cause deformation and damage to the engine components.