I'm hoping some of you guys can help me talk my way through this... The only thing left for me to do is rebuild the steering cylinders but I sure wish I had the warm and fuzzy that the cylinders were actually the problem. The seal kits are going to be expensive and the cylinders tough to remove, tough to rebuild (aluminum glands in steel cylinders ). Machine is an IR VR-90B. Clues below: 1) Steering works fine with two-wheel steer. Possibly unrelated, I notice some "hydraulic noise" in the steering column / hand pump even when the telehandler is stationary with my hands off the wheel, almost like there is fluid flowing through a relief valve or something. I also notice that a small bump to the wheel can cause it to oscillate back and forth. There is fair amount of slop in the ball joints and if you give the steering wheel a nudge, it will just bounce back and forth (i.e. a couple of degrees left, couple of degrees right where the total travel is equal to the total slop in the mechanical part of the system). 2) I've bypassed the solenoid valve and verified same behavior as when I energize the solenoid valve. When it's bypassed for crab or 4-wheel steer, the rear wheels move just a tiny bit before the steering wheel becomes hard and the engine starts to load. Letting off the steering wheel causes the engine to relax but there's no more steering at all at this point. 3) One of the rear steering cylinders appeared to be leaking near the fitting or maybe from the gland and working its way along the cylinder and was pretty wet. The rod and the rod wiper / seal were clean and didn't appear to be weeping. 4) Suspecting the wet cylinder, I removed one of the lines going to it and capped the line. I was then able to turn the wheel one direction and then back to the neutral but going the other way caused the steering wheel to harden up again. I thought maybe it was a plumbing issue that was hydralocking the cylinder. 5) I verified the plumbing to the rear cylinders was correct (see graphics below). 6) I raised the back end of the telehandler off the ground to reduce the load on the rear wheels. I was able to steer fully in both directions. 7) I removed the tee connected to the wet cylinder and capped the cylinder end (making it a straight union and isolating that cylinder entirely). I then put the telehandler partially back on the ground to provide some load on one rear wheel (and the front wheels). Same behavior as before - I could turn one way but not so well the other 8) I noticed a significant amount of slop in both ball joints where the cylinder meets the knuckle. 9) I removed the steering cylinders from both knuckles (and plan on replacing the ball joints). The rear wheels, elevated off the ground, swivel cleanly and easily by hand. The king pin / knuckle assemblies seem okay, although the wheel assembly weighs something like 800 lbs., so I would need to get a lever to really try wiggling them up and down. That's as far as I got before the sun went down... It's not quite clicking for me tonight. What's going on here?
Fixing the leaks and loose steering is always a good idea. I don’t know your machine, but the symptoms you describe with the steering wheel action is similar to when I had trouble with my steering pump (orbital valve). I spent a lot of time and went over many other things before I ended up having the valve professionally rebuilt and it solved the problem. It is very intricate and sensitive to reassembly and pressure adjustments, so I recommend either replacing or having a experienced tech examine it for possible rebuild.
Thanks @highwayghost - I was really hoping it wasn't the orbital valve* but I've been pretty suspicious after I noticed the noise and "bouncing". Where did you take yours to be rebuilt? Is that something a typical hydraulic shop can do or did you take it somewhere special? *thanks for the correction. My Case 580C service manual describes that as the "steering hand pump" but "orbital valve" seems to be the much more common name and turns up a lot more info than searching for a "steering hand pump"
That’s what I was working on, a Case 580 SL I got lucky and the machine/hydraulic shop is close to me. Located in Washington PA about 25 miles south of Pittsburgh. They’re really good and fair at what they do. I had a good experience. They rebuilt, bench tested and pressure set it. Ask for Andrew in the components department. Those valves are pretty small and I’m guessing you could ship it to them. Tap the photo for contact info