Oil leakage in the hydraulic ram will seriously affects the working efficiency of the hydraulic cylinders.
In fact, the occurrence of the leakage is mostly caused by the oxidation of the seal ring. It is Inevitable that the seal ring will be oxidized after being used for a long time.
Another cause is that the cylinders were titled placed against it’s load.The side load will damage the seal ring.
To solve this problem, prepare a new set of seals for replacing.When you remove the seals, it is generally that the oil seal is broken. You can change the oil seal. Also, check whether the liner ring is worn or not.A worn liner ring will damage the seal ring in the application.
If the oil still leak after replacing the seal ring and liner ring,then it is the cylinder liner deformation because of overloading that cause the problem.
In this way,there is nothing you can do but to buy a new cylinder.