Hello, I have a UNIMOG FLU 419 with a CASE M35C Backhoe that shares alot in common with a CASE 580E. My problem is that the boom will not hold position, it moves fast and fine, I can pull it up and lock it into the travel lock but the cylinders will not hold position, as soon as you take your hands off the boom lever it will drop down with gravity to the ground, not instantly but pretty fast. I think it is the spool valve or the cylinders? what do you think? There are no external leaks on the boom cylinders, hoses or spool control valve. I ordered a seal kit for the cylinders and have been looking at the spool valve but have not taken it apart yet. What should I start with first or should I do any further tests to determine the problem?
Welcome to HEF @slicknessindustries You could spend time doing cylinder by-pass tests, or capping off the lift cylinder circuit from the valve & moving out the dipper to see if the boom moves. But for symptoms like yours, & the amount of time involved, I always pull apart the cylinders before I look at possible valve problems. Then you know for a certainty if the cylinders are OK or not. 90% of the time, the problem lies in the cylinder - damaged piston seals or loose piston retaining bolts. PS - I'd like to see some pics of the front half of this rig
Excellent, here are some more photos.
You would certainly not have any road rage people giving you any trouble when you are behind the wheel of this! "Get out of my way!" Amazing how the hoe folds up onto the back of the truck.
Certainly, folks let me go first at 4 way stops, even if it is not my turn. It is fully street legal and insured. I do not have property to play with it yet but enjoy taking it to the grocery and parts store, I use the loader to hold grocery's. Due to it's weight, suspension travel and short wheelbase, driving it is like being an obese adult on a child's pogo stick.
Hey welcome to HEF as well. I would check for any external damage to lift cylinders. Then I would check hyd. press. for boom circuit, you may have a circuit relief stuck open. Also the load check valves which are under the circuit relief valves.
I think we have a winner for the coolest TLB.
Piston bolt is probably stretched
Got some bung plugs to plug the lines and pulled one of the cylinders apart, easy but messy and cumbersome! Here is what the piston and seals look like, piston bolt was on tight and looks to have locktite residue.
Is the other one tight also
Check the barrels in the area where they can contact the outriggers, I have replaced many of them in my years.
Still rebuilding one of the boom cylinders, the repair kit came with no instructions and came with one extra seal in my hand that I did not remove from the boom cylinder head gland; maybe it was never installed or is never used? I used kit 1543265C1 for Case 580 D.
I think it is called a buffer seal and I do not need it for my model cylinder, pulling the other side apart now .
I've been drooling about your machine for a very long time. The hoe has a lot in common with TLBs of the era. Those I've encountered have a relief valve built into the piston of the boom cylinder. To avoid leak down, remove, or repair this valve. I had a 580K rebuilt without the valve. My present 580K droops .
You are correct on the seal some later model glands used it but of course as you found out yours doesn't. If you still have a problem with leak down on boom I would check pressures on the circuit reliefs.
Well, slapped it back together and guess what? It works perfectly! Completely amazing to see it holding position now. Alrman called it perfectly. The job was physically hard and messy but pretty simple all said and done.
Glad you got it fixed