I have a Case 580 CK, serial number says it falls into 1966 to 1970. I rebuilt the steering cylinders. Had to have one rod made because Case said they are no longer available. Put the cylinders on filled the pump with oil ran the tractor a little and turned steering wheel a little and shut it off. added more oil did this several times. Had wheels off ground, they turned back and forth. Figure I was good to go so put wheels on ground and drove down the road steered just fine. I needed to go over a curb, both wheels touched the curb, then up and over the curb. Then I had no steering. I raised the wheels off the ground and by hand turned the wheels. I got the tractor home by turning the wheels by hand in the direction I wanted to go. Does anyone have any idea what could be the problem. Like with the tires off the ground why can I turn the wheels with my hands. there is no resistance when I turn the wheels all the way left, then turn the wheels all the way right. I can do that with the engine running or off. The steering wheel will not turn the wheels with the engine running.
I posted the same message on a different forum a man there gave his thoughts and was correct. The rod I had made by a Hydraulic shop, the threads that hold the piston on were too small a diameter. So the piston came off after four turns when the wheels were on the ground.
Good grief ! What a sad situation their ignorance put you in.
Have a similar problem here. Installed new parts in both steering cylinders, reassembled and filled with oil, bled all the lines, steering works fine with wheels off the ground, but not with tractor weight on them. Steering worked fine before I serviced the cylinders, and I am certain all the new pieces went back in the same order they came out. I am beginning to think I was better off with a good steering system, just a leaking one, about ready to throw in the towel.