Causes and treatment methods of excavator oil cylinder discoloration

Dec 21, 2022


Many excavator users have encountered the problem of discoloration of the oil cylinder, thinking that it is a problem with the quality of the oil cylinder.

In fact, in many cases, the discoloration of the oil cylinder has nothing to do with its quality. Next, the editor will explain the reasons for the discoloration of the oil cylinder and how to deal with it.

The phenomenon that the oil cylinder turns black, blue or purple is not the change of color of the oil cylinder itself, but a layer of colored film on the surface of the oil cylinder, so it is not the problem of the oil cylinder itself.

Normally, the cylinder will first turn blue, then darken, turn purple, and finally black.

There are many reasons for the discoloration of the oil cylinder. The following are the common reasons for discoloration.

1. There is a high temperature phenomenon in the hydraulic system. During work, the piston rod is in high temperature state (especially in the cold season) and frequently contacts with the low temperature environment (the temperature drops suddenly);

2. During the maintenance period, if the special hydraulic oil for excavators other than this brand is replaced, the discoloration of the piston rod will generally appear within a few days after the oil is changed. The reason is that the quality and performance of an extreme pressure anti-wear additive in hydraulic oil are different;

3. The blue of the oil cylinder is caused by the additives in the oil seal and hydraulic oil adhering to the cylinder rod at high temperature, and the blackening is caused by the lead-containing additive in the spray in the cup (that is, the wear-resistant sleeve) attached to the oil cylinder at high temperature on the pole. Generally, it is caused by the high temperature of the hydraulic oil, and this phenomenon mostly occurs in the first half of the bucket cylinder that is used more. We recommend that the dust on the radiator part be cleaned frequently to ensure the heat dissipation effect.

The method of dealing with the discoloration of the oil cylinder:

If there is a very small part of blue in the cylinder, you can ignore it, and it will disappear automatically after a while;

If the discoloration is serious, the oil seal and wear-resistant sleeve need to be replaced. At the same time, the high temperature of the hydraulic oil should be avoided as much as possible, and it will return to normal after a period of time.

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