Ford 861 Hydraulic System

My Ford 861 tractor loses its prime after sitting a day or so. I loosen the allen head bleeder screw on the pump and after a while the oil starts to come out and the lift begins to lift although it does not lift as high as it should even when the pump gets primed.
My first question is, where is the most likely leak causing the pump to lose prime? There is a manifold that connects the hydraulic reservoir to the pump and I assume there are o-rings in that manifold and maybe inside the pump as well.
My next question is what is the most likely cause of the lift to lose lift height with the brush hog attached. Is it just too weak or is it a worn control valve part? When I do get the pump primed, the lift works slower than it should and does not go up very high, it barely gets the brush hog off the ground!

What you describe, my 850 does, though it does hold position, it might pulse a bit at times. Last June, I put the disc harrow on, and it lifted it way high, like it should, but there have been times it would not carry my 2 bottom 101 ford plow adjusted to plow in the furrow. It will lift a heavy cast iron weight I used for ballast everytime, so I am not sure, (though I am sure its needed) the top cover needs to be pulled and some typical items addressed then adjusted in there, as well as considering the internal cylinder leaking under load, one can inspect that with the filler cap off and illuminating with light, the one time I did, don't recall seeing oil coming out of it, be interesting to hear what others say on this one, its common to these at this age, these kinds of problems.

Wayne, losing prime after sitting is the classic sign of a suction side leak. The most likely cause is one of the manifold o-rings or more likely, the wobble shaft seal in the pump. I'm assuming you have the round piston pump. When the seal is worn, most likely you will find the wobble shaft worn also.

If you have a square vane pump, parts are NLA. But the piston pump can be rebuilt. Its not too expensive, but requires a shop press and some experience in removing cup and cone bearings and races.

Can I just buy the o-rings and the shaft seal by itself? Can I replace the shaft seal myself? I remember I did buy a kit for a Jubilee I had years ago and I replaced the kit parts myself but I did have to take it in to the shop to get one of the bearing races removed. They welded around the race and it just fell out! I could not figure out how to do that!

The o-rings on the manifold are easy. I like to use the rectangular rings from CNH, they seal better.

Assuming you have the round piston pump, you can rebuild the pump yourself, but its not simple. To get the seal out, you need to remove the bearing race. As your memory told you, the best way is to weld a couple small beads on the race and it will fall out. By now the seal is well cooked as is the needle bearing. So you need a new seal, needle bearing, and main bearing race. My bet is that the wobble shaft has a groove in it where it rubbed the seal. To do it right, replace wobble shaft and bearing. You will need a shop press to press the bearing on the shaft. Don't forget a gaskets also. For the price I would get the valve rebuild kit and replace the check valve springs, they are usually well worn, that kit has the gaskets and seal. If this sounds too involved, take it to a shop with some experience on these pumps.

If you decide to rebuild it yourself, we can help.

Good luck

PS, Check your pump for cup and cone bearings, some very early pumps used on 860 had double row ball bearings. Your 861 should not have them, but you never know what has been swapped around. Parts are not available for the ball bearing pumps.

Thanks for the description, I think I understand. Sounds like I need the rebuild kit which is less than $50. I assume it contains everything I need but the wobble shaft which is another $50. The needle bearings and the welded outer race is in the kit i hope...........I will let you folks know how I am doing, but right now I am battling throat cancer and will not start on this project for awhile. I am also hoping to start building another pole barn which means my work time is limited although I am retired.

My next question is what is the most likely cause of the lift to lose lift height with the brush hog attached. Is it just too weak or is it a worn control valve part? When I do get the pump primed, the lift works slower than it should and does not go up very high, it barely gets the brush hog off the ground!

That's the EZ question the first one is harder to eliminate...

You can go thru the hydraulic fill plug and manually push the control valve all the way in... If it lifts all the way you have a adjustment issue are ware issues with the lift linkage... This test does not answer your fist question nor will fix that question... I don't have the answer to it I have not had pump issues (lucky me)

Thanks, I never heard of being able to push the control valve in by way of the hydraulic fill plug. I will look in there and see if I can identify the control valve and push it in. I imagine you are talking about a link inside that can be pushed manually somehow. I don't know what I am looking for but will try to figure it out.............Thanks much.

You can also see the control valve and the back of cylinder if you take off the round PTO lever cover (on the left side under the seat). You'll need a flash light and a mirror.

If you lift a weight and turn the tractor off. Then look inside you may be able to see the source of the leak as the load comes down. I'm betting on the piston o-ring. Easy fix if you have an engine hoist or a strong friend.

(quoted from post at 06:34:33 06/01/15) You can also see the control valve and the back of cylinder if you take off the round PTO lever cover (on the left side under the seat). You'll need a flash light and a mirror.

If you lift a weight and turn the tractor off. Then look inside you may be able to see the source of the leak as the load comes down. I'm betting on the piston o-ring. Easy fix if you have an engine hoist or a strong friend.

Click to expand...

No need to remove the PTO shift cover you can see the end of the lift cyl thru the fill hole...

I had not either... I removed the PTO shift cover that was useless I could not see chit so I took the fill plug out and to my supersize there it WUZ

I was trying to figure out a simple way to eliminate the pump/leaking o-ring are gasket as a issue versed a ware/adjustment issue... In the pix I am using a long screwdriver to work the lift linkage... I still think you have multiple issues...

They say a picture is worth a thousand words and your photo bears that out! I will try to work the control valve with a long screw driver like in your photo even though I do not know what it looks like inside and which direction to push whatever! Thanks for the help, this forum is great!

Maybe this picture will help.



Its upside down. You can see the fill hole behind the dog bone. The lever is attached to linkage back to the control valve.

....and referencing Kurt's picture, pushing the linkage/control valve toward the front of tractor (control valve into ram/valve body) is direction for LIFT.

Great photo.....Which is the front of the tractor? Is the lever to push the one in the middle of the photo with the cotter key in it? I do see the fill hole behind the dog bone! There is another lever connected to the two springs is appears.

Yes its the leaver with the cotter key that connects to the valve with the yellow dot going into the lift cyl assy...