8n hydraulics

kendallt

New User
Recently picked up a 1951 8n. three point is strong, but drops quickly when I hit the clutch or shut down.
Did some searching and found the likely culprit(s), intend to order all parts I think I'll need so I can simply bolt everything in and get back to work.
anyone have a list of what parts I should get?
And anything else I should check out while I have it opened up?

Also, I saw the lift cylinder listed here, but don't see it now, did they stop carrying it? If so, is it available elsewhere?
 
You might want to share w/ us what you think the likely culprits are. If the arms drop w/ the tractor off or the clutch depressed, chances are you have a worn lift cylinder or piston (or both), a blown top cover gasket or a leaky pressure relief valve.

Have you pulled the inspection plate to check things out?

Are you planning on dropping the pump?

nnalert's should have a cylinder.
75 Tips
 
All the parts you need for the hydraulic lift shud be right on this web site.It takes some looking as there are lots of parts. That piston can probably be replaced with one with O rings or cast iron rings. It also may be possible to replace the whole unit cylinder and piston.
 

Have not yet opened it up to inspect. Plan on doing that before I order parts.
That's what I've concluded, piston or cylinder, it's strong lifting so I've almost ruled out the over pressure valve, which seems like it would weaken the lift if it were faulty. Intend to swap it out anyway.

I don't like throwing money at things, but when I tear into them I want to know that everything is good when I put it back together. So intend to change the cylinder, piston relief valve and gaskets at the minimum.

It runs and operates well, but the person I bought it from stated that he 'bought it 23 years ago and only had to add oil once' Also said that 3 point operated the same way for as long as he owned it.
So I'm guessing that the piston and cylinder are pretty well worn if it's done that for 20+ years.
 
You might re-think not dropping the pump.

Chances are it will need a good cleaning.

If you drop the pump, plan on replacing the PTO seal.
75 Tips
 
Trouble shoot before parts and on the N series it is pretty easy to trouble most of the problem just by pulling off the inspection plate on the right side. Then with something heavy on the 3 point fire it up and watch for oil dripping down form above which is likely due to leaking cylinder rings. Also watch for area where oil is moving a good bit.
That all said many say to get the new improved NAA type piston and o-ring
 
(quoted from post at 13:40:33 06/19/15)
the person I bought it from stated that he 'bought it 23 years ago and only had to add oil once'

If they didn't change the oil in 23 years, the hydraulic sump is probably full of all sorts of nasties.

With the top cover off, drop the pump (easy part of the whole job) and clean everything well. The safety relief valve is easier to replace on the workbench (no stubby wrench needed)
 
(quoted from post at 12:40:33 06/19/15)
Have not yet opened it up to inspect. Plan on doing that before I order parts.
That's what I've concluded, piston or cylinder, it's strong lifting so I've almost ruled out the over pressure valve, which seems like it would weaken the lift if it were faulty. Intend to swap it out anyway.

I don't like throwing money at things, but when I tear into them I want to know that everything is good when I put it back together. So intend to change the cylinder, piston relief valve and gaskets at the minimum.

It runs and operates well, but the person I bought it from stated that he 'bought it 23 years ago and only had to add oil once' Also said that 3 point operated the same way for as long as he owned it.
So I'm guessing that the piston and cylinder are pretty well worn if it's done that for 20+ years.

I would say you have the situation well in hand but clean it well while you are at it.

TOH
 

I'll take the advice of pulling and cleaning the pump and everything.
Biggest problem I have so far is finding a cylinder, every place that has them listed has also marked them out of stock, or on back order. Only find them on Ebay, and I don't care for Ebay.
 
About 95% of the time all you need to do is install a new NAA type piston and o-ring and not replace the whole cylinder. Those cylinders are so easy to work on even a 8 year old can do one
 
I would not rule out the pressure relief valve..I had two within a short period of time
that lifted and worked ok except they fell as soon as you clutched it..Both had bad
pressure relief valves..you have a leak somewhere and it could very well be the PRV..Do the
clear tube test on the PRV..look inside through the inspection plate hole and if you don't
see a steady stream(leak) from above, checkung the PRV would be the next thing I did...
 


I'm not certain, but think I may have solved the problem.
Went out to look inside pulled the cover and all I saw was a very slight drip from above. While inspecting anything I thought looked interesting, I noticed the the plate the quadrant is mounted is slotted, and there were 'slide' marks from the bolt heads, and that it also had a set of match marks stamped in which were almost a full 3/8 inch off.
Checked the manual and it had the adjustment procedure in it, so I stuck my hand in and slid the quadrant back till it felt right inside, looked up and the match marks were aligned. Started up, raised the hitch shut it off then played with the dog for a half hour, then got something to eat, and it's still up an hour later.

Not certain that it's actually fixed, but looks like it's doing what it should do.

Definitely need to change the fluid though.
 


Does seem to be working correctly now, stays up approximately 6 hours after shutting down.

New issue, now the only way it drops all the way to the ground is if I move the draft lever forward. when it's in normal position control, the 3 point only drops a bit over halfway down.
 
(quoted from post at 13:55:41 06/23/15)

Does seem to be working correctly now, stays up approximately 6 hours after shutting down.

New issue, now the only way it drops all the way to the ground is if I move the draft lever forward. when it's in normal position control, the 3 point only drops a bit over halfway down.
ight first try backing off a bit on that quadrant adjustment you made. If no joy there, it will be internal linkage adjustments & probably a cam pin.
 

I'll do that. Still plan on tearing into it and replacing any worn parts I find.
Pretty sure I need to clean out the sump too, I reached down to the bottom and there's maybe a half inch of what feels and looks like axle grease on the bottom. The fluid itself looks pretty clean otherwise.
 

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