hydraulic lift help

Ok, I have an older Rotary mid rise hydraulic lift.

For some reason lately the ram wont go to full extension and give full rise.

Tonite I disconnected the ram from the lift and verified the lift itself is not binding, it will raise to full height.

The ram, even without a load only goes to about 1/2 extension. I removed the bleeder in the ram and nothing came out and it still doesnt move beyond that point.

I checked that fluid was topped up in the pump.

Not sure where to go from here. I had emailed Rotary a few months back but never got a response. Anyone with any knowledge on this things want to give me some ideas?

weak pump?

Ranger50 wrote: weak pump?

Doesnt seem to be, runs strong and then just "hits a wall" like its clogged. I think I may need to bleed the pump but I cannot find any information on how to do so.

This weekend Im going to disconnect the line from the ram and see if the pump runs ok without the ram attached.

In reply to JThw8:

Listen to the pump, if it sounds like it is building pressure or hit the relif valve then the cylinder could be binding. The other and more likely cause is a leaky cylinder. I rebuilt the cylinder on my lift and it was not bad. It cost about $20 for seals and $100 for hydraulic fluid. I had trouble figuring how to get mine apart tell I took it to one of the heavy equipment mechanics to show me how to get the end cap off. It was a metal wire fed into a groove thru a slot in the O.D. of the cylinder (If you have this type you will see what I mean just pull out that wire while turning the endcap). I was lucky that mine had a little scuffing but sealed right up, been in service for two years since the repair and no leaking or drift when left in the up position above the locks.

yes, when it hits the "bind" point it pumps/cuts/pumps/cuts like its fighting against something. It does seem like the cylinder is binding. I have it disconnected and cannot pull it out by hand (but dont know if I should be able to either) The end cap on mine has flats in it so it looks like a big azzed wrench should do it. I guess that's the next thing to work on.

Got a few projects firing up over the winter so even if I need to buy a new cylinder its worth it but I dont want to parts swap troubleshoot either. Not even sure I'd know how to source the proper hyd cylinder to be adequate for the system

so I let it sit for awhile with the ram extended and the bleeder out and went back out and hit the pump and it pushed past whatever the issue was and pumped alot of fluid and crap out of the bleed port and went to full extension.

From this I assume the piston seals are leaking and fluid got past it and "hydro locked" the cylinder. For now I can just open the bleed port and drain it occasionally until I can get the right seals to rebuild the ram or just spring for a new ram.