Why should the screw cap nut be tightened repeatedly after disassembly?

First of all, why should the cylinder head nut be repeated? This is because the cylinder head gasket is an elastic asbestos product, and its sealing function is sealed by its own elastic force. If the elastic force is too small, or disappears, it will not seal, causing air leakage and even failure of the cylinder head gasket. When the cylinder head is used for too long, or if the pressure is too large or too small, the elastic force will drop or disappear, and the above failure will be formed. When the newly replaced cylinder head is operated for a period of time, the spring force is lowered, so that the elastic force is insufficient, the pressing force is reduced, and the sealing effect is reduced, which causes air leakage and further flushes the cylinder cushion.

Secondly, the cylinder head is made of cast iron or aluminum alloy, while the cylinder head bolt is made of alloy steel. They have different coefficients of thermal expansion and a large coefficient of bolts. When tightening for the first time, it is in the cold state. When the engine is working, the temperature rises and the bolts change relatively. At this point, the pressing force becomes smaller and the air leaks.

Therefore, after the new cylinder head and the number are maintained, the cylinder head nut should be re-tightened. The time of re-tightening is to work after 34 shifts, or when the mat is finished. For the cylinder head of cast iron, it should be in the state of the car, that is, immediately after the flameout; the cylinder head of the aluminum alloy should be re-tightened in the cold state. The order of recombination is still in a symmetrical crossover manner and can be tightened to the specified torque.

Re-tightening the cylinder head nut in this way ensures that the cylinder head gasket can also extend the service life of the cylinder head gasket.

Take appropriate safety measures, do not be personally dry, in case of being injured by the falling parts. In addition, when drilling under the vehicle, the foot should be extended outside the road to prevent the vehicle from being crushed.

When the seven bogey repairs, the engine does not turn off. When the vehicle is repaired in the wild, the engine should be turned off. If the vehicle is not turned off, the accident is often lurking. For example, a rotating fan blade may injure people; under the running vibration of the engine, it is possible to change the locomotive from a braking state to a non-braking state, causing the locomotive to suddenly slip.

Due to environmental conditions, there are often unclean factors in the field repair, that is, the parts are not clean, the work tools are not clean and the hands are not clean. To ensure the quality of the repair, you must be fully aware of the importance of keeping it clean. In addition to trying to make the site tools and hands clean as much as possible, the parts can be washed in place using a container such as a washbasin plastic bucket.

Nine bogey does not check before the start of repair. Before starting, you should carefully check whether the repair parts are small parts such as gaskets and nuts, whether the fuel oil and cooling water are filled according to the regulations, whether the shift lever is placed in neutral, the car After the front of the car and under the car, if there is anyone, and press the horn alarm, then you can start the start, wait until the cutting operation is normal, and then enter normal driving.

Guizhou Agricultural Mechanization

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