Oil leak on engine crane

[Anguz]

Used my sip engine crane couple of weeks ago...on lowering it, it leaked from the top of the pump.
It only appears to leak when lowering under load.. the weight of the crane on its own it does not leak...
Assume that it's either a proper seal or an o ring
Its a generic Chinese ram . Are seal kits available?

 

[m_c]

There shouldn't be much pressure behind that seal, especially while lowering.
Is there a vent plug plug further up the ram that might need removed, as tank pressure build up could cause oil to be forced out the weakest point?

 

[Dapph2]

There shouldn't be much pressure behind that seal, especially while lowering.
Is there a vent plug plug further up the ram that might need removed, as tank pressure build up could cause oil to be forced out the weakest point?

It will still have the raised load weight on the fluid .

Getting new seals can be a real nightmare so many slightly different profiles and dimensions from thiousands of outlets . Bespoke seal could be the expensive answer . I've chucked several Chinese hydraulic cylinders away as a consequence of the screw thread for the cap not being at the correct vertical line up and the cap going on slightly lobsided ( this one was on a £600 ish 500kg motorcycle lifter platform ) .

 

[m_c]

It will still have the raised load weight on the fluid .

The ram on these is also the reservoir, with the reservoir being a second tube around the actual ram tube, and it's quite common for them to have a removable bung for a vent, which if not removed (some need removed, some need slackened, some get supplied with an actual vent plug to be fitted, while some just rely on plastic plug) can cause problems/leaks.

 

[roofman]

Dont they have a ball bearing and a spring which is seated and acts as a check valve, might have a bit of dirt under the seat.

 

[Kram]

How much of a leak? Just weeping or is it peeing out?