05 Cat 257b Hydraulics leaking down .

[Daddygoose51]

I have just repowered my machine with a brand new Perkins motor, so that's out of the picture . My hydraulics all four cylinders slowly leak down over time. And that's an issue when I'm running along and loosing height on my attachments. I also noticed the other day that when i was on a pretty good slop i stopped and the machine was slowly easing down the hill until i hit the parking break. With all this said , is it possible that a relief valve is leaking by causing this? and would this same problem be associated with loosing hydraulic power after running the machine for several hours?

 

[ianmcolo]

I think you have a couple of issues: 1-the cylinders leaking could be a: seals around the pistons in the cylinders or b: a relief valve in the control valve. C-Your control handles could be bypassing oil activating the lift and tilt spools. Both functions lift and tilt have their own circuit with a common high pressure relief. They also have their own port relief valves also. 2-with the machine slowly rolling down a hill could be an issue with drive motors or in the pump. The drive system is separate from the lift and tilt functions but use the same oil. 3-loosing hyd power after running for a while-as things heat up, they expand and oil gets thinner. Pull the hydraulic off and check for anything shiny like metal flakes, if you see metal then you have an issue in the pumps. If the oil is good then you will need to start diagnosing each thing one at a time.