B21 3 point failure

[Ozarkorange]

I have a 1998 B21 and have no lifting power with my 3 point arms. They Will raise without any weight attached but I can push them back down with my body weight. The hydraulics to my loader all work properly, and when I attach the backhoe those functions all work correctly. When I raise the arms and close the control valve the arms are locked in place and I can’t force them down so I feel like it is working correctly. When I raise the arms and Move selector rod from 3 pt to backhoe the arms immediately fall on their own so I think that valve is working. When I raise the arms and lift the front of the tractor off the ground with the loader the arms fall on their own until I release the loader handle.. I’m not sure what that means. I have changed the hydraulic filter and transmission filter,, changed out the super udt2 oil, cleaned the in tank screen, and took apart the pressure relief valve to see if any trash was in there. I was using box blade when it failed and that happened once before but it just started working again. Anyone else have this problem? Any advice would be greatly appreciated

 

[lugbolt]

On the back of the tractor there are two levers behind the seat that you use to choose between backhoe and 3ph. Try moving them in or out to see if the 3ph functions normally.

if not, get your pressure gauges out, and your service manual and go through it. The manual outlines the system operation fairly well, and gives decent enough instruction how to test it.

probably have either a leaking piston or weak hydraulic pressure, which could also affect the loader.