Last fall I replaced the broken ring and pinion on a 1979 JD 410 backhoe. After I got her up and running I blew a line to the loader bucket, replaced the line and then lost hydro pressure. It should be worth mentioning that the system was "open" for months and it I feel that it got dirty.
I had posted in here last fall and some good people where kind enough to help.
I guess the best way is to list out what I have done so far.
1. Tested the pump pressure with the rear hydraulics plugged off at the power-steering T and the pump read about 2400psi. As well I have 130psi at the reverser control.
2. Replaced both filters (tranny and hydro).
3. Cleaned the transmission screen.
4. Cleaned the transmission relief valve.
4. And just yesterday completely disassembled and cleaned the speed gear assembly (reverser) control.
Still nothing. Pump still reads only 500psi.
One thing I did notice yesterday is the hydraulic pump to pressure control valve seems hot while running. Other lines seem about the same as outside temp. I know someone had mentioned that a hot line points to the leak / problem, but where? Does that mean the pressure control valve is leaking?
Some of the things I am thinking of looking at today.
1. Bypassing the steering. Someone here suggested it.
2. Try to understand the loader control valve and clean or bypass it. My thinking is that if the loader line blew would not a influx of oil pass through the loader control valve, possibly picking up dirt and thus creating a leak?
3. Revisit the pressure control valve, due to the pressure control valve to pump line being hot.
Other then that I am at a loss here. Any help or other ideas would be greatly appreciated.
Thanks in advance.