1954 Ford NAA Hydraulic Problem

[1954NAA]

I have a 1954 Ford NAA. I have had the tractor for 30 years and it was missing the hydraulic pump when I got it. Someone made a plate to cover the place where it bolts to the engine and had cut and brazed the lines at the back of the tractor. I decided to try to get the hydraulics working. I got a used pump and got a set of lines and repaired them. I installed the pump and lines on the tractor but the lift would not raise. I got and watched the hydraulic repair for ford tractors video before taking off the lift cover:

Steiner Tractor Parts - - VID18D - HYDRAULIC REPAIR, FORD TRACTOR

I replaced the cam follower pin, changed the rings on the piston, cleaned the control valve, unstuck unload valve and replaced o-ring on the unload valve and I replaced the safety valve with this valve:

Steiner Tractor Parts - - FDS353 - HYDRAULIC PUMP SAFETY VALVE AS

I replaced the steel ball that goes in before the safety valve.

I put a hydraulic gauge on the pump and can see that I have over 2000 psi pressure when I raise the lift handle, but the lift will not come up. If the raise the lift by hand the pressure will drop when I reach the position that the lift handle is set at. So this part seems to be working correctly, when it reaches the desired level the pressure drops, even though I am raising it by hand.

I am not sure what to try next. I saw something about a check valve and a back pressure valve but I don't even know where they are located on the lift assembly:

Hydraulic System

Any way to just plug the safety valve temporarily to see if that is the problem? Any other troubleshooting tricks? Any advice would be greatly appreciated.

 

[Soundguy]

DO not plug the safety valve.. it's a ball / spring arangement anyway...

 

[1954NAA]

Soundguy, I see your name showing up a lot in these forums. Would you mind looking at this thread?

1954 Ford NAA Hydraulic Problem - Yesterday's Tractor Co.

Some new information has been added.

Thank you.

 

[Soundguy]

already seen it.. can't add much more than jmor already has, at this point.

 

[Guesseral]

When you raise the 3pt arms by hand and the pressure decreeses do the arms stay up after you let them go? If they stay up when you release them that means that the piston has traveled that far and is holding the short plunger at that spot, it also means that you are getting a very limited amount of fluid through the port at the piston just not enough to push the piston out with the weight of the arms, and that is a very very small amount of fluid. I am trying to remember the system it's been a few years since I did mine so if I use a wrong term please excuse me. I have the IT manual at home and they discribe the propper way to check the pressure and it is from the side of the rear housing if I am not mistaken. By taking the pressure at the pump you are only checking the pressure at the pump not at the rear where the pressure is utalized. I think the desired pressure is 22XX lbs don't remember the exact number. If you are not getting pressure at the rear and have it at the front then there may be a blockage between the pump and the rear end.
If you don't have the IT manual you should get one they were a life saver for me, you can get one at most tractor supply stores at the rack by the rear desk or in with the books I have seen then in both places, pick up any ford book and look at the back it will tell you what number book you need. I will look at mine tonight and see if I can jog my memory.

 

[Guesseral]

Hydraulic System

Here look at this diagram it shows the valves you were looking for, now this is just a typical diagram but it shows and lists the operation of the system.

 

[Soundguy]

there are really 2 systems in play.. the check valve and the pump.

if you lift the arms manually, and fluid is allowed to enter the cyl and move the piston out ( minimal pressure.. only few pounds needed, then when you let go of the laod and it holds.. thent he check valve is holding pressure in the piston / cyl. safety valve is likely good.

something ahead of it must be bad.. ie.. relief.. or unloader not moving enough, or stuck nearly unloaded..