1939 Ford 9N Hyd. Question

Casey Keele

New User
Has anyone on here heard of bleeding air out of the hydraulic pump. I have just rebuilt my pump and cylinder including a new piston and rings. before I started the hydraulics worked but were making noise and would not hold up an implement with pto off. now after rebuild hydraulics dont work at all or come up so slow it takes 10 minutes for them to rise up completly. I have pulle it apart 4 times now and cannot find a problem with it. Relief valve and control valve are working. Linkage is all working. no leaks from cylinder when running looking through inspection plate. I am at a loss and frustrated. I cannot figure this out. any help is appreciated.
 
if the lift came up once.. it's primed.

open the inspection port. see if the t valve is moving fully in / out with lift handle.
 
"Has anyone on here heard of bleeding air out of the hydraulic pump"

No bleeding required.

"now after rebuild hydraulics dont work"

Be a little specific; what exactly did you rebuild?
 
Hcooke I rebuilt the whole pump. New cam blocks, valves, springs, basically everything is new except the pump housing. I put in a new piston in the hydraulic cylinder. the cylinder had no scoring on the inside. I changed the old three steel ring out to the NAA 2 o-ring style. Soundguy if by t valve you mean control valve, yes is is working. I did however notice now that everything is rebuilt the control spring behind the seat is loose. Ofcourse it is frooze where i can't get it off. I know from experience not to force stuff on these old tractors unless your goal is to break it. I may try to heat it and see if it will come loose. Anyone ever tried some 5/8" washers as a shim to tighten it? just a thought. And could that control spring being loose really take away from the linkage moving enough to engage the lift?
 
anyone also got a trick for hooking the control valve up between the forks. it might just be me and my gotilla hands but that is a real pain doing it through the inspection holes. I got it after 45 minutes of grunting and cursing but was thinking i am doing something wrong.
 
no magic unfortunately. it's just like you said. and if ya got big paws. yep.. it can be a fight.
 
I have found in my old age that the easiest way to reconnect the control valve arms is through the drain hole with needle nose and screwdriver or what ever it takes. Use safety goggles to keep oil from dripping in your eye.

Are you sure you didn't put the valves in wrong or maybe the gaskets backwards in the champers?

Gasket on the pump base with the pressure hole in the wrong place?????

Zane
 
If the draft spring is far enough out of adjustment it can cause the lift not to function properly. I showed somebody a couple of weeks ago in my tractor. I stood on the lift arms and I would turn the yoke on the plunger by hand. The lift would either not pick up, work perfect, or the arms would stay up and not come down depending on how far you screwed the yoke in or out. The yoke adjustment is what pulls the control fork up against the control lever rod. That adjustment is there to take up the slack as the pad at the top of the fork and the end of the control lever rod wear. You will find that on most tractors the yokes are frozen in place with rust. Get a torch and heat the yoke until it is cherry red and it should turn. Take it completely off and clean the threads real good and apply grease to the threads and reinstall the yoke and take up any slack between the yoke and spring. Check to see if the lift works, if it does hook up an implement and lift it. When the implement is at full lift check the draft spring. You should just barely be able to turn it by hand. If there is more slack than that you need to tighten the yoke some more. Once you have the spring properly adjusted loosen the four bolts on the quadrant and slide it all the way rearward. Measure 2 1/2" from the top of the control quadrant and make a mark on it. Raise the implement all the way up and then move the control levers forward edge to the mark you made. Then take a pry bar and slowly slide the quadrant forward, when the implement starts to drop tighten the four bolts on the quadrant and recheck it because sometimes tightening the bolts will cause it to move. Sorry for being longwinded but that"s the proper way to adjust the lift according to Harry Fergusons shop manual. Yes you could add shims to the spring but why not do it right and be done with it?
 
Thanks for the info Zane. I did put gaskets on right and I took it apart and rechecked thinking either the gaskets were blocking holes or something was blocking the tube running up to the cylinder. Everything was good. I did a good clean and flush of the sump area and soaked and cleaned the pump while i had everthing apart and out. I am going to try the control spring that Jason Suggested it is so looses i can move it around. unfortunalty it was rusted on so i will torch it and adjust it and see if that works
 
I don't think the looseness of the big draft spring is going to be your problem with it not lifting. The draft linkage can't go back any further than the anchor plate under that spring no matter how loose it is.

I would look at the spring that connects between the front of the ram cylinder and the center (Knee) section of the control arms. If that spring is weak it will not allow the control valve to be pushed forward with any pressure.

First thing I would do is to reach in and push those control legs forward with the PTO running making sure the control valve goes all the way forward.

One other thing I've run into a couple of times is the intake port in the control valve bushing being blocked by some foreign material. It that little hole is blocked it never will lift till it is cleared.

Did you remove the control valve bushing from the housing?

When the control valve spool is moved forward it opens the intake port and when it is moved backwards it opens the exhaust port. Intake port is toward the back of the bushing and the exhaust is toward the front of the bushing.

I have encountered times when the lift would not go down and found that the exhaust port was blocked with some sort of plastic like from an oil container.

Zane
 
Ended up being the spring that goes from the hydrualic cylinder to the control fork. i put in a new spring and the lift started working. goes up and down just fine....has a little jerky motion to it but will lift 500 lbs with no problem and no noises.
 
Zane,
Did as you suggested and it is the spring that is not strong enough to pull back on the knee of the forks. Running into a problem finding a spring to replace it. I did get one at the hardware store but it has too much tension. Apparently these must not go bad often because i have searched high and low and no one carries a replacement.
 

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