Auxiliary hydraulics not holding pressure

[Moonshadows]

I have an s770 with about 2200 hours in it, still a nice tight machine! I think it was used for a while with a shredder head. I meant ion that because it might be related to my problem. I posted a while ago because my grapple bucket would not hold in the open position (it would slowly close, it still does this but it used to maintain a tight grip on the load now it's loosing its pressure (slowly opening) It seems the pressure is bleeding off, if it where a valve seat issue it would have positive pressure Is there a pressure bypass in the system? My guess is there is and that bypass is not seating (or maybe wornout from the extended use of the shredder) and allowing to pressure to slowly bypass. I used my backhoe attachment on a small job the other day and although everything works I don't think I'm getting 100% power (seat of the pants measurement compared to my old machine) Any suggestions or thoughts are appreciated —— thanks scott

 

[Moonshadows]

FIXED It turns out the "push to release pressure" couplers wear out internally and bypass pressure. New couplers and it works perfect

 

[waugh111]

FIXED It turns out the "push to release pressure" couplers wear out internally and bypass pressure. New couplers and it works perfect

Thank you Moonshadows for posting your results. I am having the same issue. Grapple leaking down and also not holding grip. Also a wood processor that loosens grip on the clamp arm and the splitter head force has weaked to the point of not splitting logs. I understand a coupler leaking internally causing the grip to loosen while the hydraulics are in "neutral" but to lose power with the spool valve fully engaged in the hydraulic control valve is hard to understand. I think I will go ahead and replace the couplers because it's hard to argue with results but can anyone explain this to my simple mind.

 

[waugh111]

Thank you Moonshadows for posting your results. I am having the same issue. Grapple leaking down and also not holding grip. Also a wood processor that loosens grip on the clamp arm and the splitter head force has weaked to the point of not splitting logs. I understand a coupler leaking internally causing the grip to loosen while the hydraulics are in "neutral" but to lose power with the spool valve fully engaged in the hydraulic control valve is hard to understand. I think I will go ahead and replace the couplers because it's hard to argue with results but can anyone explain this to my simple mind.

I just read on another thread that when the coupler is pushed and the pressure relief is activated that it sends the fluid(pressure) down the case drain line. That makes perfect sense. I didn't know there was a path that linked to the case drain internally within the coupler block.

 

[Moonshadows]

I just read on another thread that when the coupler is pushed and the pressure relief is activated that it sends the fluid(pressure) down the case drain line. That makes perfect sense. I didn't know there was a path that linked to the case drain internally within the coupler block.

Sounds Like you got it figured out, I hope your machine works well now! Mine has been perfect since replacing the fittings!! (I even used the cheap eBay fittings, no complaints)