8N hydraulic lift won't stay up

I have a later 8N (side mount distributor). When I lift an implement on the 3 point, in this case a 6 foot disc, it will not stay up while transporting it. The lift slowly bleeds down. My other worn out tractors, 2 Fords and a Ferguson will bleed off a little bit but will pump back up. This 8N does not pump back up unless I drop the lift lever all the way down and raise it again. The PTO is running all the time that the lift is bleeding down. This is a major pain when I am transporting, especially when I am on the road as I have to stop the tractor to re-raise the implement without damaging it or the road. I have never had one of these apart and would like a few suggestions as to what to look for and what parts to have on hand before I tear it apart. Since my shop is the all season kind with no roof, no walls, no heat, no shade tree, and has a dirt floor I am hoping this can be a one day repair. I do have several repair manuals, I & T and some Ford reprints.

Thanks
thelonepatriot
 
(quoted from post at 20:55:28 11/21/15) See tip #16 at the link. Post back with what you find.
75 Tips
I grew up on Ford tractors, two 8n's and a Jubilee. All of them as well as the two 8n's, the 3000 and the TO20 I currently own have a bleed-down issue which I am sure is being caused by one or more of the issues listed in tip 16. The 8n I am asking about is the only one that will not pump back up after dropping a little bit with the tractor running and the PTO engaged. All of the others will pump back up after dropping about an inch. I think it is something mechanical that is bent or broken or out of adjustment that is not telling the lift to pump back up. I have to let the lift lever all the way down and raise it again to get the lift to come back up. It comes back up at a normal speed. I have not tried adjusting the quadrant as the chisel marks are lined up.

Since my shop also has "passive air conditioning" as well as the other previously listed features, the tractor will have to wait until spring for a teardown. Passive air conditioning is whatever the condition of the air is that is passing through at the time. Right now it is snow and wind and well below freezing. I'm not as young as I used to be. Hot chocolate and toast are preferable to working out in the "shop" at this time.

Patriot
 
" Hot chocolate and toast are preferable to working out in the "shop" at this time."

Amen. And it's 50* here today & I'm cold.

" I think it is something mechanical that is bent or broken or out of adjustment that is not telling the lift to pump back up. "

You have a dirty pump.

When the weather improves, drop it & give it a good cleaning.

With all of the fluid drained out, block the front wheels & get the rear wheels up at least a foot. (you'll see why soon enough) Remove the 4 bolts holding the PTO shaft in & pull it to the rear & out of the tractor. Loosen all of the bolts. Remove all but 2 corner bolts. Then, carefully remove them. If you are lucky, the pump will drop free (and dump a pint or so of hydraulic fluid down your sleeves). If not, wrestle it free. The pump has 'ears' that fit into the housing; wiggle it a bit & it will drop free. If you have the rear tires a foot or more off of the ground, you will have enough arm room to hold the pump & lower it at the same time. Put it on your work bench & remove the safety valve (p/n 638) and the control arm lever (p/n 643) which will allow you to remove the intake & exhaust valves (p/n?s 640 & 698) Drop all of it in a bucket of diesel (or mineral spirits) or your parts washer & let it soak overnight. Once it has a good soaking, get it on the bench & start blowing it out w/ compressed air. Run cleaning fluid into the hydraulic discharge near the test port & make sure you get a good flow out the small hole in the side of the pump were the control valve fits. I don't see much need to pull it down any further just to clean it. But, I always replace the safety valve (p/n 638, about $25) Reinstalling the pump is harder than pulling it out because you have a gasket to worry about. (no sealer on the gasket) And, you will probably need a helper to guide the control rod into the pump rocker shaft unless you?ve done this 6 or 7 times before!

While you have the PTO shaft out, it would be a good time to replace the seal on it. It's got two spring clamps around it. Take your needle nose pliers & remove the one in the front. Then, hang the shaft & bearing housing in your vice & tap the butt end of the shaft; the bearing cap will come off (and the shaft will land on your foot). Then, remove the other spring clip from the other side of the bearing. At this point, remember that you never bought a seal driver & go get a BF socket & drive the seal out. If you have the new style seal, the white side goes out. (open side to the oil) Put some grease on it.

Contrary to conventional wisdom, not a lot of water gets in the oil from the shifter boot. Of course, if it's bad, replace it, but you get water from the draft control spring & the dipstick. But, most water is just a byproduct of the heating/cooling cycle of the oil.

You?ll need a pump gasket, safety valve, inspection plate gasket(s), PTO seal, PTO gasket, gasket sealer & 5 gallons of fluid to do all of the above.
 

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