Hydraulic Lift Woes - 841S

Two winters ago, I got my grandfather's 841S. I spent the second half of that winter getting it as field-ready as I could (had the front end completely off and replaced, as well as many other things, most of which you can find in my past posts). This past winter, I split the tractor to replace the clutch and fix some other odds and ends. I have already been given my project for this winter: the hydraulics.

The lift arms don't work at all in draft control mode (regardless of where the control lever is, they immediately fall to a lowered position), and work "funny" in position control mode. Even though the position control lever moves freely throughout its range, the "lifting action" only occurs around the last 10-15 degrees of motion from having the lever "all the way down" to "all the way up." The lift arms also "leak down" when the tractor is running when the arms are in any position except all the way up.

That being said, the lift arms are quite strong, and work quickly. I also have a remote hydraulic valve, which works fine. So I think my pump is in good shape.

When I go to take my top cover off and delve into this beast, what should I be looking for? Are there any tips I should keep in mind? I have both the red Ford shop manual and the IT manual, but I've learned they're written for people with far more mechanical knowledge than me.

Of all the things I've worked on on this tractor, the hydraulics make me the most "nervous," simply because I feel I have the least amount of prior knowledge about how they operate when compared to the other systems I've repaired on this old gal.

I have used the knowledge I've gained on this forum to help a friend of mine bring his dad's 850 back to life, so I'm very grateful for your continued help!
 
Sounds like you have more then just one problem but 2 or 3 all making thing work wrong. Lift cylinder is probably needing to be rebuilt. Plus cam follower pin plus adjustments made and even the unloader valve o-ring replace for good measure
 
My experience is limited to repairing just a few hundred series hydraulic issues. I am a curious boy and don't like going into anything in the blind and much less going by the standard pattern answers... My TIP that may ease your questions and make you more comfortable before you go looking for a needle in a hay stack... In this post you will see how I went about determining how to quickly determine a adjustment/ware issue in the linkage... I manually worked the lift linkage with a long screwdriver threw the hydraulic fill plug hole, I also found out you can see most of what you need to see with out removing the dreaded PTO leaver and standing on you head looking for leaks..

http://forums.yesterdaystractors.com/viewtopic.php?t=1218671&highlight=fill
 
Why is the pto lever "dreaded"? Is it that hard to get off? I've been planning on taking mine off so maybe you can enlighten me on this procedure. Also, does it have a gasket that needs replacing when you put it back on?
 
(quoted from post at 09:09:12 09/05/15) Why is the pto lever "dreaded"? Is it that hard to get off? I've been planning on taking mine off so maybe you can enlighten me on this procedure. Also, does it have a gasket that needs replacing when you put it back on?

It will come off no problem other than have a pan ready to catch oil and hope all the bolts cooperate... Its a operation I dread there has to be a better way and there is its looking you dead in the face...

I removed the PTO cover looked with all my fancy tools it did not answer my questions... Put it back on with a few bolts drove to were I had a implement I could hook up, hooked up and still had questions... Put the cover back on drove it back into the shop stood there and scratched my arse ... Hummm...

If you knew what you were looking at I did its still not as EZ as it sounds it still left unanswered questions... I removed the seat the fill plug seamed to interest me I removed it and there it wuz all I needed to see what I needed to get at to be in command of this operation "Hiding in plain sight". Like when you are looking for mustard in the fridge... it is right in front of your face but you simply don't see it. :lol:

I don't know why we are having this conversation when the answer may just be hidden behind the fill plug... I was able to steer this beast with a screwdriver I was in total control most of my unanswered questions were answered I found the mustard the bottle was cold the light came on when I opened the door no farther diagnostic of the operation of the fridge were needed :wink: I then knew were to focus my attention once I had the cap off the mustard bottle and the mustard flowed as it should...
 
(quoted from post at 10:05:05 09/05/15)
(quoted from post at 09:09:12 09/05/15) Why is the pto lever "dreaded"? Is it that hard to get off? I've been planning on taking mine off so maybe you can enlighten me on this procedure. Also, does it have a gasket that needs replacing when you put it back on?

It will come off no problem other than have a pan ready to catch oil and hope all the bolts cooperate... Its a operation I dread there has to be a better way and there is its looking you dead in the face...

I removed the PTO cover looked with all my fancy tools it did not answer my questions... Put it back on with a few bolts drove to were I had a implement I could hook up, hooked up and still had questions... Put the cover back on drove it back into the shop stood there and scratched my arse ... Hummm...

If you knew what you were looking at I did its still not as EZ as it sounds it still left unanswered questions... I removed the seat the fill plug seamed to interest me I removed it and there it wuz all I needed to see what I needed to get at to be in command of this operation "Hiding in plain sight". Like when you are looking for mustard in the fridge... it is right in front of your face but you simply don't see it. :lol:

I don't know why we are having this conversation when the answer may just be hidden behind the fill plug... I was able to steer this beast with a screwdriver I was in total control most of my unanswered questions were answered I found the mustard the bottle was cold the light came on when I opened the door no farther diagnostic of the operation of the fridge were needed :wink: I then knew were to focus my attention once I had the cap off the mustard bottle and the mustard flowed as it should...

lol...funny stuff
I'm a curious george too...always gotta peek behind the curtain. I remember years back...860 I think it was...had the bobs..looking in the fill plug hole with a strong light...look at that..the mouth of the cylinder...with a small stream coming out...lol well that ain't right...end of diagnosis at least.
 
It sounds like from what problems I've described and from what I'd seen and read on here that I'll be needing to go ahead and take off the top cover, in any case...
 
There are five things I would do if I took the top cover off.

1. Replace all the top cover gasket and o-rings that come with the top cover gasket kit.

2. Replace the cylinder o-ring and back up washer. They will come with the top cover gasket kit, but I prefer to get them from CNH. Just my preference.

3. Inspect the cam follower pin. If it is not is good condition, in other words - no wear, replace it.

4. Replace the unloader-valve o-ring. Again I prefer the CNH o-ring over the one in the top cover kit (my preference).

5. Check the linkage adjustment according to the I&T manual.

This covers most of the problem areas. BTW, if you remove the the control valve, do not use abrasives or a wire brush to clean the bore or the valve. This is a metal to metal seal. Clean with extreme care.
 
Regarding the parts that you prefer from CNH vs. those found in the kit:

Why the preference? Are the kit parts not up to spec?
 
(quoted from post at 07:39:43 09/24/15) Regarding the parts that you prefer from CNH vs. those found in the kit:

Why the preference? Are the kit parts not up to spec?

I prefer the leather back-up washer for the cylinder piston that CHN supplies instead of the fiber one that comes with the Tisco kit. I usually get the CHN O-ring too, its cheap insurance. I know others have good luck with the Tisco parts, so its just my preference. If you get the leather washer, soak it in hot water before you put it on. If you try it dry you may break it putting it on. Also, a piston ring compressor will help get the piston back in the cylinder.

On the unloader valve, that O-ring is critical and an odd size. One come with the Tisco kit, but trying to separate it from the pile of O-rings in the kit is difficult and I'm just never sure I got it right.

I usually just get the CHN back-up washer, piston O-ring, and unloader valve O-ring from Messicks. Not expensive, and they ship quickly.

Hope that helps.
 

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