I recently purchased a 1974 Case 580B backhoe. I have never owned a heavy equipment before so I am learning. The machine was setting for quite awhile before I got it. I've been working on repairing the dozens of leaks all over the machine and I still need to completely flush the Hydraulic fluid (white). Right now I am working on the backhoe and I noticed that when I tuck the backhoe up into the normal driving around position (not lock) the boom (for lack of a better word) sags and the bucket uncurls. If I am parked go up on a hill and I have the backhoe swung to ether side it will swing down hill over time. In less then a half of an hour it will sag to the ground. This is a lot of drift for it to be cylinders pistons, no? If I pull just the control valve to bring the boom back up the the bucket will curl back up with it. If I just swing the backhoe to ether side after it has sagged close to the ground, the boom will come back up and the bucket will curl back up as it is swinging. Is this a problem with the control valves? According to the drawings there is no rings or gaskets for the valve spools in this model. Is the only fix to replace the valves? Are there trick/methods for determining what the problem(s) could be? Thank you for any and all help, BigBoyNow. (My mommy said so!)
They were prone to o ring failure on the load check assemblies underneath the secondaries and will allow interaction between the circuits. (use only Case replacement rings) One thing to check is for bent barrels on the boom cylinders from colliding with the stabilizer cylinders when swung with the stabilizers raised or dropped over a raised stabilizer leg. I have replaced many barrels and pistons.