NAA Hydraulic Trouble Shooting

[Erik Graham]

Greetings;

I have a NAA Jubilee which will now barely hold up my 5' bush hog unless the tractor is at about 1/2 throttle. Hydraulic fluid levels are fine. What I would like to know is whether the tractor hydraulic pump is at fault or whether the lift cylinder needs a rebuild. How can tell which one is the culprit? Unfortunately I don't have a loader or any other hydraulic device on the tractor to eliminate one choice or the other.

Thanks, Erik

 

[SSdoxie]

Will it lift the bush hog up with engine at idle? If so I doubt either pump or cylinder are the problem, more some small leakage in the "hold" position of the valve.

 

[J_J]

I don't know specifics on that tractor.

In general a hyd situation. The 3pt cyl is designed to lift and hold the 3pt linkage, and implement. The pump forces the fluid into the 3pt valve, and the valve directs the fluid to the cyl and returns to neutral. If the piston seals are good and the relief valve is not leaking, and the safety valve is not leaking, you would expect the cyl to hold.

Pump could be weak and not pumping the potential pressure.
The 3pt valve could be leaking.
Piston seals worn.
The relief valve could have some trash in it.
The safety valve might have some trash in it.

Does the 3pt try and leak down after the lift is raised?

 

[LD1]

Does the 3pt try and leak down after the lift is raised?

Try this:thumbsup:

If it leaks down, it is probabally NOT the pump. It would either be the valve or cylinder.

The cylinder is easy to check cause IF I remember, it is like the 8n's. The cast cover under the seat, that covers the rear end and has the 3PH rocker arms comming out of it, that cover has the cylinder on the underside of it. You can pull that cover off and inspect the piston/cylinder/seal. If that ist it, it is probabally the valve.

If it lifts and holds, it is probabally the pump.

 

[Erik Graham]

Thanks for the replies. I've only used the tractor twice this year and that was a couple of weeks ago. What I recall is that it takes more than an idle to raise the mower. Once it's up it doesn't stay up very long before sinking down and then it seems as if the hydraulics sense this somehow and then mower jerks up again. In the event the position valve or relief valve are shot are they a big deal to replace? I'm moderately mechanical but the tractor is in a remote location with no cover and no hydro.

Thanks, Erik

 

[jinman]

In the event the position valve or relief valve are shot are they a big deal to replace? I'm moderately mechanical but the tractor is in a remote location with no cover and no hydro.

Thanks, Erik

Erik, since you have no experience and no manual, the best advice any of us can offer is for you to continue to use the tractor as-is until you can get it to a suitable repair shop. It's hard enough to work in a remote location when you know what you are doing. It's a recipe for disaster to do that without knowing. I think you need a lift cylinder seal, but doing a simple thing like removing the lift arm pins out of the clevis can be a beast. Those things get rusted in and don't want to budge. You will be no better off if you get the tractor about 1/2 disassembled and have to give up because of an unseen problem. Wait until you can get some qualified help. Plan on a repair in the near future, but don't let overconfidence cause you to end up with a mess on your hands in a remote area. That's the best advice I can give.

 

[Soundguy]

yep.. could be pump is weak and bypassing, OR alot of leaks bleeding off the entire 2.9gpm flow.

check valve might leak.. cyl seals could be shot out so oil goes in and out.

time to buy a manual first of all.

then lift the arms witjh no load, then add a load and see if they settle with machine turned off.

soundguy

 

[hankmass]

Could someone point me to where I can buy a Hydraulic manual for a Ford NAA. I think I have a pump problem and need a parts breakdown picture.
Hankmass in Lake Wales, FL

 

[Soundguy]

there is no 'hyd' manual. tghere is a ford service manual, and an aftermarket service manual. ( the master parts catalog has exploded diagrams )

if you merely need the diagram.. go online to CNH and hit the parts section.. you can pull up every diagram in the master parts catalog...

 

[peterbiltz71]

Hey guys, if the lift arms work with no emplament and will only raise some of the distance with and leaks down when engine is shut off then what? I have changed a $500 pump, changed oil and cleaned the screen but no luck. I have a Hinamoto E230 and its being a pain. I am looking for a rebuild kit for the lift piston but haven't had any luck yet. Can you guys let me know if I'm headed in the right direction?