noisy hydraulic pump

[DAVE`]

I just recently purchased an 860 ford.I found that after it ran for 10 to 12 I began to hear a rather loud noise at the rear of the hyd pump.I have checked cam shaft end play and changed the drive end of the pump assembly.I have also made sure I have some backlash between gears. I have also removed the stack valve and put the plate on to eliminate the remotes as any part of the problem. The pump works fine and the noise will stop when the loader is raised or lowered but using the 3 point lift arms does not change the noise. I am stuck and would sure appreciate any help. Dave in the Hoosier State,

 

[Anonymous-0]

Usually valving has bypasses. Perhaps yours doesn't and your hearing a relief valve buzz.