Ford 801 lift issue

Good morning all, I'm new to this forum as well as tractors so please bare with me...
I recently purchased a Ford 851 that had some issues but I got a good deal on it and I've been handy with a wrench so I decided to give it a go. The problem I'm having is my lift comes up but I can push the arms down by hand even while the engine is running. It could probably lift less than a couple pounds if need be. Also it seems to be lifting to the highest point regardless of where the handle is set. I've read about the lift cylinder o rings as well as the safety valve, but before I jump into that I wanted other opinions.
Any help is appreciated!
 
couple possibilities I see.. so you will need to take a look in and see if it has a massive leak at the cyl mouth or cyl block..
or not.

if a massive leak, then repair is usually simple tear it down and re oring, reseal, etc.

if no big leak detected, then it could be stuck perhaps mostly unloaded and the residual oil flow is causing it to lift but
resistance makes it leak off faster than the residual oil can keep the load lifted.
 

Makes perfect sense to me. My question would be then, why does the lift come up even with the handle in the down position?
 
uh.. re-read my post. Remember.. this is an unloader style system. your 3pt handle does not directly hard link to a control valve.
 
(quoted from post at 07:56:14 05/31/16) uh.. re-read my post. Remember.. this is an unloader style system. your 3pt handle does not directly hard link to a control valve.

Yes I see now. I misread earlier. Thank you

Unrelated, I currently have 13.6 rear tires but they are in bad shape and found a great deal on some 12.4's. good idea or no?
 
Simple question:

Are you in position control or draft control mode?

What is the position of the little lever on the right side of the top cover under the seat?
 
OK, I'm thinking you have a major leak, probably on the piston to cylinder O-ring.

I would pull the round PTO lever plate under the seat on the left side. Start the tractor and lift an implement. Stop the tractor. Then look in the opening. With luck you should be able to see oil leaking out of the end of cylinder. A mirror and flashlight will help.

If you see that, then it is time to pull the top cover and replace the O-ring and backup washer. Not a bad job, but a bit intimidating the first time.
 

Awesome, thank you for the input. Will try asap. Currently i have the fuel tank off getting an exhaust leak fixed as well as replacing a leaky valve cover gasket. Then I will be ready to tackle the lift cylinder issue
 
(quoted from post at 10:05:56 05/31/16)

Unrelated, I currently have 13.6 rear tires but they are in bad shape and found a great deal on some 12.4's. good idea or no?

I have 12.4's on my 850. Not stock, but I replaced the six loop rims with hat rims from a NAA (narrower rim). Plenty effective for a mower/ light blade work tractor, but may appear small to some.
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I think about these parts way too often. Here's a discussion of some hundred series hydraulic issues with clear photographs. These concern 600 series tractors but I'm not aware of significant differences between the hydraulic operation of 600 and 800:

http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=ford&th=528000 schematic: http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=ford&th=591691

Many other great threads about diagnosing three-point problems on this site.

When you get the cover off, it helps to think of the unloader valve as a relay, i.e., the quadrant lever actuates the control valve via a linkage. Movement of the control valve hydraulically actuates the unloader valve. The re-positioned unloader valve permits hydraulic flow to the cylinder.

Three-point problems I've repaired

Unloader valve can stick in "bypass" -- no pressure
Piston o-ring can fail -- no pressure
Pump can fail -- no pressure
Line 'tween pump and sump can leak --no pressure
Other valves in system can stick "open" -- no pressure (but I've never had that problem.)
Then there's the linkage adjustment; but that doesn't sound like your immediate problem.

My two cents. Good luck.
 
I think about these parts way too often. Here's a discussion of some hundred series hydraulic issues with clear photographs. These concern 600 series tractors but I'm not aware of significant differences between the hydraulic operation of 600 and 800:

http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=ford&th=528000 schematic: http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=ford&th=591691

Many other great threads about diagnosing three-point problems on this site.

When you get the cover off, it helps to think of the unloader valve as a relay, i.e., the quadrant lever actuates the control valve via a linkage. Movement of the control valve hydraulically actuates the unloader valve. The re-positioned unloader valve permits hydraulic flow to the cylinder.

Three-point problems I've repaired

Unloader valve can stick in "bypass" -- no pressure
Piston o-ring can fail -- no pressure
Pump can fail -- no pressure
Line 'tween pump and sump can leak --no pressure
Other valves in system can stick "open" -- no pressure (but I've never had that problem.)
Then there's the linkage adjustment; but that doesn't sound like your immediate problem.

My two cents. Good luck.
 

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