Hi all! I’m having a heck of a time with this mini ex. I started noticing I was getting fluid leaks on some cylinder fittings when I would put the boom in a bind. I decided to check my hp pressure on the valve body and it would jump to 4,000 psi quick and if you held the joystick longer it slowly creeps to almost 6,000 psi. I thought it was a bad relief valve but new one did the same. So I turned it down not to hurt anything again. Now it will jump to 2000 psi and slowly creep after to the 3770 psi which is what it should be. I checked pressures when I first got the machine and it would quickly jump to the 3770 relief pressure and relief pressure was not touched since. No matter which way I turned the relief valve it will jump to a certain psi then slowly creep after. I tried changing the pump but same result. All functions on the machine work fine. Nothing is slow. It’s just that the HP or LS pressures are not correct and doing the same thing. Could it be the directional valve? Any advice would be appreciated .
Seems like load-sensing system malfunction, NOT relief valve or pump. pump displacement adjusts based on load demand via pressure feedback signal. When working correctly: Pressure jumps quickly to exact load requirement, Holds steady via LS compensator, Relief only activates if system overloads Your pressure creep indicates that LS compensator spool can't properly regulate pump displacement, allows pressure to build uncontrolled until relief finally dumps it or Shuttle valve failure: Selects highest LS signal from multiple functions, if it's stuck it will sends wrong signal to pump compensator Install gauge on LS port (small line from valve to pump), should track ~200-300 psi above load pressure. If erratic/delayed, LS circuit issue confirmed. Inspect LS orifices: Small orifices in valve body can clog and can causes sluggish LS response (pressure creep). Test shuttle valves: Located in valve body, select highest pressure signal or stuck shuttle = bad LS feedback
Thank you for your reply. Things keep snow balling with this machine. The new pump upon installation made a loud whining sound every time I use any of the functions. Now no functions work and it’s like the pump just went out. This was a pump from Friday Parts. Not Volvo. I slowly worked all functions to bleed air but maybe I didn’t do it right.