I have a 1986 case 580 super E TLB with 2400 hrs on it. It has a hydraulic problem. The boom leaks down when not running and when I try to pickup a load the boom will not hold but the digger will. There are no external leaks on any of the cylinders. When lifting loads the boom falls away until I pull back on the boom lever, then it will stop falling but not lift up. The machine has case controls. I had the machine serviced at the dealer two years ago, but have only put on 50 hrs. All fluids are where they should be. I think it is in the control valves. Thank you for your time. Farmer 140
I edited your thread title to give everybody a clue as to what the thread is about. Hopefully somebody will be able to help. And welcome to Heavy Equipment Forums.
Sounds like your pressure reliefs are way out of wack. Have never had a Case anything except for my new CX210C that didn't need the hydraulic reliefs checked and brought up to spec. I would have first guessed your cylinders were in need of rebuild but unless it has 12,400 hrs on it they should be okay. I think checking the port reliefs should be pretty straightforward. Our old 680E had ports down on left side of engine frame. Get yourself a service manual and a good 4000 psi gauge. When you check the backhoe if it is any less than 2000 psi that's probably the problem. To isolate the cylinders, cap the lines to the cylinders before you check and then hook them back up and compare. If very close, then the reliefs are the problem.
Most likely one or the other boom cylinder piston needs repacking, the other good possibility is a failing port relief valve, you can identify the valve section by following the hoses, try swapping the top and bottom relief valves in that section, see if the boom function improves or not. If it's easier and the hoses are long enough and have the same ends on them, for testing you can swap the two hoses from the valve to the boom cylinders.
I would look at the boom cylinders tube real good. More than likely the cylinder tube has hit the stab foot or outrigger. This will ding the tube and cut the piston and seals inside the cylinder when it makes a stroke past that point. I am not saying it's not a load check or relief but 99% of the time it is a contact issue with the stab leg or pad. If it has made contact you may also have trash/ metal shavings/ packing material in your relief also.