641 hydraulic problem

Shelbydave

New User
Hi
I rebuilt my 641 cover and put something back incorrectly. When starting the hydraulics raise the arms immediately no matter the lever position or draft position. the only way to get the arms back down is to loosen the accessory plate on the front and oil will seep out. I put something back together wrong and don't know what. I did remove the check valve with a puller. I did not remove or touch the unload valve in the cylinder. Can anyone help
DZ
 
What exactly did you do when you "rebuilt the cover"? Did you follow the procedures in the service manual for adjusting the internal control linkages? Was the cam follower pin worn, and if so, did you replace it?
 
I did not change any of the adjustments on the position control rod or the draft control springs from prior to disassembly.
I replaced all o rings, as well as gasket / ring on the piston. I did install a new cam follower pin.
I removed and reinstalled the hydraulic control valve and am sure thats in the correct location.
 
The reason why started this originally was the tractor would take a while to raise the hydraulics and then eventually stopped raising them at all So I went through and replaced all the overwings and obviously put something back together wrong
 
(quoted from post at 17:14:45 12/19/20) Hi
I rebuilt my 641 cover and put something back incorrectly. When starting the hydraulics raise the arms immediately no matter the lever position or draft position. the only way to get the arms back down is to loosen the accessory plate on the front and oil will seep out. I put something back together wrong and don't know what. I did remove the check valve with a puller. I did not remove or touch the unload valve in the cylinder. Can anyone help
DZ
ure sounds like control valve notbeing positioned to "lower". Linkage & adjustment problem.
 
You should always go through all of the adjustments when you have the top cover off just to be sure, especially if you are replacing the cam follower pin and the history of the tractor is unknown. Chances are good that a previous owner adjusted things to compensate for the worn pin if it was working at least close to properly when they did work prior to your work, so the odds are that you need to adjust things back since it has a new pin.
 
So I had to make some adjustments To the hydraulic control valve bushing can someone tell me the order in which The check valve goes in how do I post photographs
 
(quoted from post at 12:45:10 12/20/20) So I had to make some adjustments To the hydraulic control valve bushing can someone tell me the order in which The check valve goes in how do I post photographs
fKvaTBv.jpg
 

That helps a ton thank you. The shop manual has the first section after the spring backwards from your picture
Going to reassemble and see how it works now.
Dz
 

Success
Hydraulics function correctly. Thank You for the replys and help. I still have som slight seeping between the small cover assembly and main cover at the front. I replaced the 8 o rings, but I'll order another set and try to get it to seal properly
 
(quoted from post at 13:44:06 12/20/20)
Success
Hydraulics function correctly. Thank You for the replys and help. I still have som slight seeping between the small cover assembly and main cover at the front. I replaced the 8 o rings, but I'll order another set and try to get it to seal properly

It's funny that this post is not that old. I had this same exact issue with my 641. The initial issue was that the 3 pt did not rise all the way, only about 1/4. Tore the whole top lid apart. Replace all O-rings, cam pin, even milled and pressed in a new bushing on one of the linkage levers and adjusted the linkage to Ford's specs. In total I have a easily 4 whole days (96 hours) on the lid rebuild, 90 of those hours troubleshooting the issue in this post. This post is a life saver and should be more readily available. I even went to a Ford tractor repair center and their head mechanic didn't even have a clue as to what was causing this constant lift issue. I also called JD productions and talked with Dan, he never once brought up this fix. I never have like Fords, any Fords, and this just reaffirms my feeling towards them. If my tractor wasn't an inheritance and family heirloom I would probably sell it for any other brand (personal vendetta). Because of this post, I was able to fix the issue in 15 minutes. Now my hydraulics work perfect. On a side note. During all this my 3pt was pulsing when lifting. I rebuilt the pump and it still pulsed. After flipping the backpressure valve the pulsing went away.
 

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