8n lift problems

[jdman2009]

I’ve got a 8n that’s got lift issues. The lift raise up when you put the pump in gear and won’t go down regardless of where you put the lever. It’s got a few worn pieces I’ve replaced the pin that rides on the cam. Question is does that still relate to something in the cover or something with the valve on the pump? Is the valve that moves to raise or lower the lift supposed to move back and forth freely or is it supposed to be spring loaded? I know how the linkage and everything adjusts I’m more familiar with later 600-601 and so on but not these . If anyone came give me advice on the valve spring loaded or not would help. It seemed like it was to begin with but I’m not sure if something was just stuck. Doesn’t seem like lift cover rod is moving the valve lever on the pump enough to me. Thanks for the help!

 

[R Geiger]

The control lever is not spring loaded. if it is something is wrong!

 

[jdman2009]

So lever on the pump should move freely?
The cam on the lift cover is wore bad I’ve got one coming hopefully that’s causing the problem. Ether way it needs changed.

 

[TheOldHokie]

So lever on the pump should move freely?
The cam on the lift cover is wore bad I’ve got one coming hopefully that’s causing the problem. Ether way it needs changed.

The exhaust valve in the base of the pump is not opening. The position control cam has nothing to do with that. The shop manual describes the operation of the valves. If I hsd to guess the spool is stuck and/or the linkage is brokem.

Dan

 

[jdman2009]

The exhaust valve in the base of the pump is not opening. The position control cam has nothing to do with that. The shop manual describes the operation of the valves. If I hsd to guess the spool is stuck and/or the linkage is brokem.

Dan

Ok what’s the purpose of the springs behind the intake and exhaust valves to keep them pushed out against the lever? Like I said I’m not that familiar with these and it doesn’t say anything about them in the manual. The intake stays pushed in flush with the pump.

 

[TheOldHokie]

Ok what’s the purpose of the springs behind the intake and exhaust valves to keep them pushed out against the lever? Like I said I’m not that familiar with these and it doesn’t say anything about them in the manual. The intake stays pushed in flush with the pump.

AFAIK the only purpose.of the springs is to create an elastic connection in the linkage. If the exhaust valve opens the lift will come down. Replace nnalert with N tractorclub.com

https://nnalert/howtos/pdfs/Rocky Carr's tutorial on N Series Hydraulics.pdf

TOH

 

[soaked]

Hi guys,
Agree, the exhaust valve must move forward in its bushing far enough so the tapered end is open to the two ports in the bushing.
This is the exhaust valve, taken apart.

The spring is inside the spool, pushing the rod to the rear of the spool. It helps the arcing lever smoothly push the valve forward.
( or pulled rearward)
It doesn't push or pull on the control arm.
If the spring broke, the valve wont move forward enough to drain the fluid.

There were two versions of the intake valve, newer one has the longer taper.
Its spring DOES push rearwards against the lever--- but not much force.

Exhaust valve is pinned onto the lever.
Intake valve spring is pushing the lever to the rear.

 

[jdman2009]

With my lever like that my intake valve is still pushed back in the pump. Broke spring or stuck I guess.

 

[Btzj02]

One of the pumps I worked on I found the cotter pin behind the control valve spring missing. New cotter pin and new spring fixed my problem.

 

[jdman2009]

I found the spring for the intake valve but can’t find one for the exhaust. I looked and noticed other people had the same problem finding one. I’m sure there’s one somewhere if just knew what to get.

 

[soaked]

The spring is 9n 632.
8n Exhaust valve assy came in 5 different sizes 8n 640-A2,,, 8n 640-B,,, 8n 640-C,,,
8n 640-D,,, and 8n 640 -E.

None have been available new, for a long time.
Have you got the pump out and found the spring busted?
Maybe can find an acceptable generic spring?
The control rod needs to move the lever rearward to push the ex valve forward, to lower the 3 point. With the pto not turning, can you move the lever by hand, to see if the arms will drop?( need towel to dry hand)

 

[soaked]

Its also possible the 3 point is seeing pressure from the pump (from stuck intake) at the same time the exhaust valve is WORKING. So it kind of "hovers"
Instead of falling.

 

[TheOldHokie]

Its also possible the 3 point is seeing pressure from the pump (from stuck intake) at the same time the exhaust valve is WORKING. So it kind of "hovers"
Instead of falling.

i also considered that. I dont think the pump can produce enough flow to do that but an easy test is turn off ths PTO.

TOH

 

[soaked]

i also considered that. I dont think the pump can produce enough flow to do that but an easy test is turn off ths PTO.

TOH

If an intake valve is stuck at full lift, and the linkage is only moving the exhaust valve to LOWER a little,,,, was my thought.

There was a post years ago where a pump had the intake valve installed backwards, and the exhaust valve was reassembled in the wrong order, with the spring put in first, then the rod. Made the assy much shorter. Arms went up with down command, and down with up command. IIRC it "hovered" at a certain position....

 

[jdman2009]

The spring is 9n 632.
8n Exhaust valve assy came in 5 different sizes 8n 640-A2,,, 8n 640-B,,, 8n 640-C,,,
8n 640-D,,, and 8n 640 -E.
View attachment 148998

None have been available new, for a long time.
Have you got the pump out and found the spring busted?
Maybe can find an acceptable generic spring?
The control rod needs to move the lever rearward to push the ex valve forward, to lower the 3 point. With the pto not turning, can you move the lever by hand, to see if the arms will drop?( need towel to dry hand)

I’ve got the pump out now. The exhaust side moves fine the intake has the valve pushed in stuck. I haven’t tried taking the rest apart yet. When I turn the pto off or stop it the lift goes down but soon as I turn it on it raises straight up with no control or problems just can’t stop it or make it go down while the pump is pumping.

 

[soaked]

OK, so the intake is stuck in.

From post #1
"Doesn’t seem like lift cover rod is moving the valve lever on the pump enough to me."
Did your control arm move the lever in the full down command so the exhaust valve was pushed all the way in, when pushing by hand? (like in the last Pic in post #7?)
Is your control arm straight or does it have a curving bend?

 

[jdman2009]

OK, so the intake is stuck in.

From post #1
"Doesn’t seem like lift cover rod is moving the valve lever on the pump enough to me."
Did your control arm move the lever in the full down command so the exhaust valve was pushed all the way in, when pushing by hand? (like in the last Pic in post #7?)
Is your control arm straight or does it have a curving bend?

It’s just like that one except my valve is stuck in the housing.

 

[TheOldHokie]

It’s just like that one except my valve is stuck in the housing.

JMOR and Hobo have both posted info on how to fix stuck spools. See what you can find ising the search tool. Or PM Hobo.

TOH