I vote to -at most- wrap an "oil pig" absorbing wick around it and forget it.

 

If you decide to repair it.. Remove all the parts you can and wash the oil out. Grind paint off and grind into the area that's leaking a little. Weld, paint, put everything back inside. It doesn't take much to seal a small pinhole like that so don't go too crazy with the grinding.

 

i've built up shafts and worn parts that have been submerged in gear boxes, rear ends etc. Even, when they look clean, there has been oil impregnated in the steel. Major contamination when striking an arc. I've taken a torch, and cooked the oil out, and have watched it smoke and oil bubble out. Eventually it stops smoking and boiling, then I could weld it w/o oil contamination/porosity. Most don't believe me when i tell them that though. But I'd think your up against the same thing.

 

This was a quick and dirty fix on a hydraulic cylinder leak the customer didn't want to spend the money (or time) on getting done right. The cylinder was fully assembled when I did it. Ground out the crack a little bit and ran a quick pass with 1/8 7018 over it. There was still a little hydraulic oil weeping from the crack when I welded over it. Didn't have any visible porosity in the weld. As far as I know it held because the cylinder didn't come back to the shop. I wouldn't recommend this as a general practice but every now and then you luck out.

 

This was a quick and dirty fix on a hydraulic cylinder leak the customer didn't want to spend the money (or time) on getting done right. The cylinder was fully assembled when I did it. Ground out the crack a little bit and ran a quick pass with 1/8 7018 over it. There was still a little hydraulic oil weeping from the crack when I welded over it. Didn't have any visible porosity in the weld. As far as I know it held because the cylinder didn't come back to the shop. I wouldn't recommend this as a general practice but every now and then you luck out.

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In the past, when we've had someone do a "quick and dirty" cylinder repair it never worked out. Often it was to provide a temporary fix to keep going until a new part arrived. We've never called the shop back to say it failed. Sometimes the cost of a quick repair is cheaper than the next day air freight on the new part.

 

If that was my press, i would remove the springs and run the rod all the way out to keep the piston seals at the opposite end of where you will be working. Remove the cylinder and drain the oil out of it. Grind the weld down where it is leaking and apply a little bit of heat with the torch, just enough to burn the oil out of the crack and then run a small weld over the leak.

 

You could try to mechanically seal it with a punch(s). Punch beside to leak not on it. It may seal or reveal a larger problem. A chisel with a small radius ground on the end so it swages instead of cuts.