High oil temperature or high water temperature of the engine is a common phenomenon. Then, when the oil temperature and water temperature of the engine are too high at the same time, what should be done?
1. High water temperature: Why is the water temperature high?
The water tank is used for heat dissipation, and this heat-dissipating method is air-cooled, that is, the fan driven by the engine.
Therefore, the reasons for the high water temperature are as follows:
1. The thermostat is stuck and cannot be opened. At this time, the water can only go through a small cycle and will not pass through the radiator.
2. The inside of the water tank is dirty and the water is not smooth. This can be used to detect the temperature of the water tank up and down by Thermometer. If the temperature below is blocked, it will be very low.
3. The fan speed is not enough and the clutch is faulty.
4. The rubber strip around the radiator is damaged or not. At this time, vortex is generated and hot air is circulated, which cannot achieve the cooling effect.
5. For the fifth point, it is easy for everyone to ignore, that is, whether the alarm will be false or not, and the sensor is broken, which is also possible. The computer is very wooden, just looking at the data without looking at the truth.
II. High oil temperature
The oil temperature is similar to the high water temperature, and it also has large and small cycles, but it does not pass through the thermostat. He has an oil return check valve. If this valve is stuck, the oil temperature will be high, and others will be the same as the water temperature.
Of course, the large excavator is driven by the fan pump fan motor to adjust the rotating speed, and there is also an overflow device, which is generally high in oil temperature. Check these places can be solved.
Let's introduce the opinions of the next expert. According to his years of experience, he believes that under the condition that the oil temperature and water temperature of the engine are too high at the same time, if the quantity of oil and water is sufficient or not much, the oil temperature should be lowered first and then the precipitation temperature should be lowered, the reasons are as follows:
1. High oil temperature does great harm to the engine
The so-called high temperature of the engine means that the oil temperature and water temperature of the engine exceed 90℃.
When these two temperatures are too high at the same time, it will affect the normal operation of the engine and bring certain harm to the engine: the gap is reduced, forming serious wear or "scuffing of cylinder bore".
The oil temperature mainly indicates the comparison between heat production and heat dissipation.
Crankshaft and bearing generate heat due to friction, while engine oil distributes most of its heat, while the balance between heat generation and heat dissipation (which is shown as stable oil temperature) is relative.
When the heat generation exceeds the heat dissipation, the bearing bush temperature will rise, the local temperature reaches the melting point of lead, and the lead in the bearing bush will melt and precipitate. When a large amount of lead is precipitated, the bearing surface of the bearing bush becomes smaller and smaller, which makes the wear worse. In severe cases, the local temperature can exceed the melting point of copper (℃), and the copper also starts to melt, eventually, the crankshaft and bearing will be severely ablated or the result of "tile holding shaft" will occur.
According to the test, when the oil temperature reaches 110℃, the oil film temperature in the bearing clearance can reach 150℃. If the temperature of oil film is above 150℃, it is easy to break and form semi-dry friction. Because crankshaft bearing is copper-lead alloy, if the reduction measures are improper, the bearing temperature will be too high and lead will melt and precipitate, and the consequences will be unimaginable.
Therefore, when the temperature of oil and water is too high at the same time, the oil temperature should be lowered first.
2. Reducing oil temperature can slow down the speed of water temperature rise
Oil temperature reduction usually adopts the method of "load reduction, low rotation speed. At this time, although the cooling liquid exchanges heat at the high temperature parts for a long time, the water flow speed slows down and the heat dissipation time is prolonged.
At the same time, due to the reduction of load and rotation speed, the heat generated by friction of various moving parts is also correspondingly reduced.
Therefore, lowering the oil temperature can not only reduce the heat generated by the engine, but also indirectly reduce the heat absorbed by the coolant, thus slowing down the speed of water temperature rise.
3. Oil temperature is one of the main factors affecting oil pressure
When the oil temperature of the engine is too high, it not only increases the fuel consumption (leakage, evaporation and combustion), but also affects the quality of the engine oil, making it difficult to form and maintain the oil film on the friction surface of various parts of the engine, as a result, main oil Gallery oil pressure cannot be established, thus increasing the wear of parts.
However, the influence of water temperature on oil pressure can only be realized through oil temperature. Therefore, it is indirect and requires a certain amount of time.
4. The first precipitation temperature has a great influence on the establishment of engine cylinder oil oil pressure
As we all know, precipitation temperature generally adopts the method of "load reduction and high rotation speed. When the rotating speed is too high, the inertia force and centrifugal force of the piston lianxuan group will be increased, making the load of crankshaft bearing plus-sized.
At the same time, the relative friction speed between the Journal and the bearing Bush will also increase, which will increase the heat generated per unit time, reduce the oil volume of the oil pump, and throw out a large amount of oil from main oil Gallery, as a result, the friction surface of each machine parts is aggravated by insufficient lubricating oil, and the oil temperature will rise further.
