I'm running a John Deere 310A backhoe. Problems started while running the boom in the air, heard a small pop and now I do not have down pressure on the boom. The high pitch noise was happening only when moving the boom or swing but is now showing also in the steering. All of the other hydraulics are working fine other than the noise. After this started, changed fluid and noticed the filter paper was pushing through the holes. Not sure what fluid was in the machine, but replaced with hyguard. Thought maybe was a fluid issue. Checked cylinder..its fine. Checked relief valve in the boom control. Appears ok. Can't find one to replace it anyway, thought maybe spring was weak, added a washer to see if shimming it would help, the noise went away but came back, no help with the down pressure. Also changed some hoses that were old, with the thought that maybe one was collapsing, no help. The other hydraulics are strong so I dont suspect the pump is the issue. You can hear the noise on the inside of the cab, but not outside the machine. Anyone have any ideas?
Did you change the filter? Possible the filter paper is now stuck somewhere in the system.
Which relief valve in the boom control did you check. Top or bottom one? If you raise boom, does it drift down?
Yes, changed both filters and the fluid, which was refilled with hygard from John Deere
We checked both relief valves, No the boom doesn't drift down. We have since removed the valve body from the machine again. Checked the spool, everything looks ok there, checked the anti-cavitation valve. Thinking maybe the spring is weak, so ordered new springs for all three anti-cavitation , that are in the back of the valves, figured go ahead and change all three while it was off. Not sure if its going to help or not. Also at one point, he switched the hoses on the boom control, to make sure the issue isn't in the cylinder, when he done that he had down pressure, but the boom wouldn't raise. My husband, had to have an emergency abdominal surgery while waiting for the springs, so have to wait for him to heal, before we can get this back together. To be continued. I'll let you know if it helps or not soon as we find out, but its going to be a while (which is driving him crazy by the way). In the mean time, if you can think of anything else, let me know.
Which relief valve in the boom control did you check. Top or bottom one? Hoping to find paper stuck somewhere, but didn't. Checked the spool, both relief valves, the anti-cavitation valves. Yes changed the filters, fluid, and checked the trans. screen which was clean. Ordered new springs for the anti-cavitation valves, hoping that it may be weak. My husband had to have emergency surgery last week, so it will be a while before it gets put back together, hoping it works. In the meantime can you think of anything we are missing? Everything else works perfectly. Also checked the cylinder, and installed new hoses, in case something was collapsing.
Problem solved. We replaced the springs in the anti-cavitation valves on the back of the valve body. They were intact but evidently weak, we replaced all three while we had it off. Got some help to reinstall the valve body on the machine. Everything works perfectly, no noise, no vibration, normal down pressure, wanted to update in case someone else runs across something like this. Thanks for your replies.