The Fordson Tractor Pages Forum

I've been subsoiling today and the valve block sprung a bad leak, the gasket having failed.
So into the workshop, remove the valve block, claen everything up, apply Heldite gasket compound to both surfaces, fit new O rings onto the block, refit the block, leave for a short time to let the compound go 'off', then tighten down.
Start engine, pto in gear, lift arms rise as they should.
Lower the quadrant but arms stay in up position. Apply my weight onto arms which then go down.
Raise lift arms again,all good. Still they will not lower without pressure. PTO still in gear
The I turn engine off and the lift arms lower on their own.

Can anyone direct me to what might be going on here?

Maybe if I do a bit of subsoiling it will clear itself ?

Thanks in advance.

I think there's a leak there, but try some work first and see. Be careful as you may get erratic raising and holding.
Sandy

Hi, does your tractor have the drop control knob fitted in front of the seat?
John

I don't think David has one as he has a 62 Super Major, the arms should hold firm with the engine off, definitely overnight, preferably a lot more, so although the drop control might slow the descent a bit it won't stop it, Super Billy doesn't survive overnight with the drop control fully closed. Billy on the other hand holds fully up for weeks (I know the Major hydraulics will hold better than the Super Major ones, as there are more moving parts on a Super Major, but Davie can hold a couple of days although he doesn't unless you bypass a leaking check valve pulling out the aux. service valve).
Sandy

I've never had a major witth a drop control so i dont know how much they slow the rate, i had an International and the drop control would just about lock the arms. Maybe an 'o' ring missing?

I have seen them squash into the hole before now, so they both restrict the flow and leak at the same time

David needs to see if the arms will hold if the aux. service valve is pulled out to see if the leak is the piston seal or the control valve (or others, but definitely in two groups separated by the aux. service valve), then he will be able to find the leak more easily, I suggest he does a bit more work first to see if there's any change, then we'll see what needs doing to sort his problem (unless it sorts itself out, which is unlikely but possible).
Sandy

Agree, as you say there's a chance it may sort itself, stranger things have happened. If not i would think the control valve would be the prime suspect, simply because it has been disturbed and the hydraulics were ok before
John

I say the control valve implying anything between the hydraulic pump and the aux. service valve, although I don't think it will be the control valve either. A leaking check valve will make gear changing difficult and it will hold the arms more when in gear and not moving, Davie does this and pretty soon we'll try and fix it. This symptom makes that easier to detect than some of the other potential leaks.
Sandy

Well thanks for the replies. I have had the valve chest off before and had no problems, why it has decided to do this now is a mystery.
The only thing that is different is the addition of this particular type of gasket sealant, applied with a brush as opposed to just a 'squirty type' of sealant tube.
I admit that I was a bit sceptical about the thickness of the sealant so maybe I just remove the block, have a new gasket and start again with the tube of squirty sealer.
Any thoughts ?
I think I will not work the tractor before I remove the block as has already been suggested, sealant may have squeezed into the ports and caused a partial blockage.
Thanks in advance

John b wrote: ↑

Sat Jul 24, 2021 11:52 pm

I have seen them squash into the hole before now, so they both restrict the flow and leak at the same time

Thanks John b, I've replied below but I think your suggestion of restricted flow may be the cause.

I suggest you find a pic of a paper gasket so you can see what needs sealing and look at the parts book to ensure the o-rings are all there.
Sandy

I have removed the valve chest ansd found quite a lot of 'gunk' under it. So have ordered a new gasket and O ring set, cleaned it all up and have to wait now for the gasket but I feel that I have put too much goo on it and it has blocked some oil way.

Lets hope it all works, I'll let you know

David

Sandy, do you think either the unloader valve or the control valve may have got some gasket sealer in it causing it to stick?

Very possibly John, but lets see if a new gasket will do the trick first.
Sandy

Yes i agree, i was just thinking ahead for other possible causes

OK,.....so I did'nt go subsoiling with sick hydraulics !!

The gasket and O rings arrived on Tuesday. I had to take the tractor to an engineer to helicoil one of the bolt holes that holds the valve chest on as I had over-torqued it and messed the threads up !

Got it home, removed all the gunge from the Heldtite gasket compound (with hindsight I had over-applied it), cleaned up both surfaces with emery cloth, making sure not to fill any ports with swarf, applied a fine surface of blue gasket sealant, put the gasket on, applied a small amount of compound onto it, placed all the O rings into the valve chest, very carefully replaced it onto the transmission, bolted it down carefully tightened all bolts and started the engine.

Hey presto, lift arms raise and lower in the proper manner. So today, I've been subsoiling with my refurbed single leg subsoiler and everything is perfect. Working down to 20plus inches, the major pulls it well, even stalled it in a very hard patch.

Thanks for all replies and advice. I've learned not to put too much sealant on ! As John b said, the gasket sealant had got squashed into the ports and interfered with the flow of oil.

Thanks again

HI,

That's good news.

Glad you got the old girl sorted and back to work!
John

Good that you're working again. Now enjoy some hard work for your Major!

Sandy

Thank you one and all
David