With the continuous improvement of diesel engine output power, the thermal and mechanical stresses borne by the piston also increase accordingly, leading to cracking and erosion of the combustion chamber wall at the piston top. Due to the effective improvement of the heat resistance of the aluminum piston top surface by the hard oxidized oxide film, it has an extremely good inhibitory effect on thermal cracking, especially on the tendency of thermal cracking at the combustion chamber edge of direct injection diesel engines. Therefore, High power pistons generally require anodizing treatment.

judge

During vehicle operation, some parts of the engine experience abnormal piston knocking noise. The abnormal sound of piston knocking on the cylinder occurs in the upper part of the cylinder, which is a rhythmic "tap" sound similar to using a small hammer to hit the cement floor. When the engine is idling, the sound is obvious and clear. Especially when the engine is running at low temperatures, the sound becomes noticeable, and as the temperature increases, the sound decreases or even disappears.

 
The locking of piston ring in the ring groove is caused by the carbon deposit generated during the oil combustion. Also, you said that the piston ring is not worn evenly. It is still burning a lot of oil just after replacing the four matching parts. It should be a quality problem of the accessories. Even if the four matching parts are replaced for a diesel engine, the matching clearance between the piston and the cylinder liner needs to be measured. Although the four matching parts are components, their factory assembly is not very careful. There may be excessive clearance, Let's take a measurement. This situation should be caused by the seizure of the piston ring caused by burning engine oil. This situation is mainly caused by the problem of parts. The technology for installing the four matching parts is a necessary technology for the repairman, and generally there is no problem. Once there is a problem, it will be more serious than this. For example, the cylinder knock, the tile scratch, and the piston ring fracture. The supplier of the cylinder pulling parts caused by the lack of water you said will not compensate for the loss. As for the problems caused by the repairman, It is not easy for laymen to judge. Unless you stop repairing in this repair shop, other repair shops will find the real reason and tell you the truth. If the cylinder liner, piston and piston ring components are replaced but the engine still burns oil, it is mainly caused by the following reasons: the matching clearance between cylinder liner and piston is too large, the opening clearance of piston ring is too large, the internal processing of cylinder liner is rough, and the cylinder liner has taper. In addition, The natural ventilation device of the diesel engine's crankcase also needs to be checked for smoothness