Clark 720 OS 20 Ton RT- Roughly 1975 vintage. Winch sprung a hydraulic oil leak yesterday, just before last lift of the day. Leaking from what appears to be some kind of pressure relief. At first, I thought it was a grease nipple (7/16" hex) but when I put my fingers on it, oil poured out more, like it was loose, about to fall out. Tried to tighten it but it just turns. Got my fingernails under the edges and it pulled out a bit and retracted like it was spring loaded. This looks to be on the horizontal centerline of the winch drum (like its on the centerline of the main shaft ), on the end opposite the hydraulic motor. Still seems to work OK but losing about 1 drop every second, so, a fairly significant leak. I'm done for the day now, but need to work it again on Tuesday (about 3 days away). I'm going to the jobsite now, to investigate further, any advice / comments welcome. Thanks, Howard
I'm not much of a mechanic so you will likely get better answers. Sounds like a breather / vent and you either have something causing a back pressure or are over filled, either with too much oil or water/ condensation.
Looking in the Manual - Troubleshooting section - Yes, this appears to be a vent plug and "Winch leaks a large volume of oil through the vent plug. - This is caused by the hydraulic oil leaking into the winch through the Hydraulic motor seal or a damaged O-ring in the winch brake". I think I'll be taking the Hydraulic motor off and having it re-sealed.