Many excavator users have encountered the problem of discoloration of the cylinder piston rod of the excavator. They think that the quality of the cylinder is a problem and they are worried. In fact, discoloration of the cylinder piston rod of the excavator is a very common phenomenon. In general, the piston rod will first turn blue, then deepen, turn purple, and finally turn black. So what is the reason for the discoloration of the oil cylinder of Doosan excavator?

　　There is high temperature phenomenon in the hydraulic system, and the piston rod frequently contacts with the low temperature environment in the high temperature state;

　　During the maintenance period, the hydraulic oil that is not special for the excavator of this brand is replaced. This phenomenon usually occurs within a few days after the oil is replaced. The reason is that there is a kind of extreme pressure anti-wear additive in hydraulic oil with different quality and performance;

　　In the process of piston rod electroplating, because of the uneven temperature control, cracks appear on the surface of electroplated layer in the later stage of work. The irregular small cracks can be seen when the surface of piston rod is observed with a high-power magnifying glass.

　　The bluing is caused by the additives in the oil seal and hydraulic oil attaching to the cylinder rod under high temperature, and the blackening is caused by the additives containing lead in the spray in the wear-resistant sleeve attaching to the cylinder rod under high temperature.

　　If the piston rod of the oil cylinder appears a very small blue color, you can leave it alone, and it will disappear automatically after a period of time; if the color change is serious, you need to replace the oil seal and wear sleeve, and try to avoid the high temperature of the hydraulic oil, and it will return to normal after a period of time.

　　There are also some special cases. When changing the engine oil, some residual engine oil in the engine can not be discharged cleanly, and mixing will occur. If it's too deep, consider whether the inside of your engine is clean. You should know that the engine oil not only has the function of lubrication, but also has the function of cleaning.

　　Secondly, the possibility that impurities can cause discoloration of oil cylinder is relatively small, and the main reason is that the oil temperature is too high, which can cause discoloration of oil cylinder. Generally, it is an old machine, mostly because the internal leakage is too large, which causes high oil temperature. Different brands of hydraulic oil may be used. Hydraulic oil of different models may cause discoloration of oil cylinder

　　Here we tell you that it is a very complicated thing that the oil cylinder of excavator changes color. As long as we can find out the reason, we can get rid of the disease.