I have a John Deere 4755 that keeps leaking hydraulic fluid from the steering axle. I have replaced the seal multiple times and the shaft seems fine, what else could be causing this? I have disassembled the steering valve and there is some dirt on the piston and bore, but the springs and balls seem fine. I thought maybe the metering valve was being over-pressured by the steering valve.
The steering return oil passes through the metering pump, through the check valve that you tapped. then on its way to the return oil pan. The reason the seal is leaking is that the pressure in the return is too high. (my theory) I would plug the hose from the gauge valve to the return oil pan and install my own hose from the gauge valve to the oil fill at the rear. So test the direction and see if it keeps dripping. With the oil pouring directly into the crankcase there should be no problem with the steering seal.
There is a place in the return sump to put a gague. From what I have been able to see in a few pages the pressure should not exceed 20 psi.
So either there is too much volume of oil coming back from the steering, or there is too much back pressure in the return line. I’d say there is too much back pressure in the return line. Perhaps you could find a place to pour the oil without going through the return manifold.