FSM Hydraulic lift problem, help!

[4040t]

Hello again,
It seems I have yet more problems with our 1961 FSM!
I have searched the forum, but have not found a specific answer to my problem so far.

In short, we did our first just for fun ploughing event last weekend. On the Saturday all seemed fine with the hydraulics and everything worked as it should including the draft control. It would also hold the plough up over dinner time with no noticeable drop.
Just before departing on the Sunday I noticed the plough was going up and down 6” by itself in qualitrol mode. I put it into normal lift mode and it promptly dropped down to the floor!
We made it home ok in qualitrol mode with the plough going up and down.
I have started to have a look at what the problem may be and the manual states to check various things before taking the top off.

The first thing checked was the check valve. The ball seems fine with no obvious visible damage to it or the seat ( part 39/45 fig 210) (I did not take the seat out though).

The next thing I checked is the flow control valve as per the manual (part 74 fig 210)
It is stuck solid in the casting, though there is no sign of any corrosion in the bore or on the end of the valve.
It seems to be stuck all the way in, so this is the main question.

Does anyone know how you are supposed to get it out? According to the manual it would seem it should just pull or drop out. There are no threads in the end so you can’t pull it out with a bolt.
Is this valve very important to the correct operation of things?
The only thing I can think of to do is to turn up a bit of bar and loctite it into the bore of the valve, then try to pull it out with that.
I’m guessing this valve has been stuck for some time.

Tomorrow I will take the pressure relief valve apart (part 46 etc fig 210) to see if anything’s wrong. It does bypass ok when the lever is moved to the top of the quadrant.

I’m sure the lift lever feels different than it used to when not in qualitrol, it seems loose with no resistance and naturally seems to want to go downwards, could this be a sign of a problem inside the casing?

I don’t think the ram seal is leaking as if the lever is in a position it likes, it seems to hold the linkage up ok.

The tractor hasn't done very much work for some time so perhaps this hasn't helped things.

Sorry for the long post, once again, any help/advice would be much appreciated, thanks

[Brian]

Think you have a linkage problem, The only thing you can do is take the top off and check. Flow control, PR Valve and Check Valve will not give the problems you have. You also have to remove the "Snail Cam" and shaft before the flow control valve will come out.

[4040t]

Think you have a linkage problem, The only thing you can do is take the top off and check. Flow control, PR Valve and Check Valve will not give the problems you have. You also have to remove the "Snail Cam" and shaft before the flow control valve will come out.

Thank you Brian
I did take the top (external) flow control lever and a through shaft out (parts 71 and 82) Would these be the parts you describe?
Though the bits I took off didn't seem to have any bearing on the valve. Does the tapered protrusion that fits underneath the lever (i think it acts as a stop) have to be removed?

Many thanks for your help