The Fordson Tractor Pages Forum

Hi all. Another colonial newbie!

Ongoing hydraulics problem. These were not working at all when I got my Dexta. The initial problem was a sticky control valve that I've freed and this at least gave me a usable (just) tpl. Problem was that I've put up with last 5cm action on the control lever until a few days ago when I finally decided to do the adjustments. I wish I'd read the forum more thoroughly because after adjusting and reassembling and it still not being quite right I found the info about the position control arm pin. So... off came the lid again last night. And, yes, mine is worn half way through. Now, to my questions while it's in this state. By the way, I'm no real mechanic but will give things a go.

1. After doing the adjustment, the hydraulics seem to be very weak. I have a set of forks on the tpl and while it lifts these and a pallet OK, it fails to lift with any real load. If I have it fully up and stand on the pallet and jump, I can drive the tpl down just with my extra weight. I can't really see why this would change by just doing the adjustment. Any thoughts? I will remove the main cylinder and check the seal.

2. I have two leaks. One is between the flow control valve housing and main cover - hopefully just O rings. The other seems to be between the flow control housing and the restrictor control lever. This one worries me more as I recall reading a while back of care needed in this area and just wanted some advice before I break something while trying to fix it.

3. Where the piston rod connects to the ram lift arm, the pin is a snug fit in the lift arm but loose in the rod (maybe 1-1.5mm smaller than hole). Is this normal or a problem.

Thanks in advance for any advice and thanks to the community for such useful info both here and on Stefan's site.

Welcome to the board.

3 .. Normal, that is how it should be.

2 .. Sounds like "O" rings, could have an effect on 1.



1 .. Adjustments will not affect your lift or drop. You may have a piston seal problem or see 2. You may also have problems in your flow control. If possible, it would be useful to try another flow control/auxiliary chest unit if possible.

You do not say how you cleaned the control valve. If you used any form of abrasive on it you may have terminally damaged it and this could give you your problems too. Did you also remove the plug near the control valve and free off the unload valve.

Hi Brian. Thanks for coming back so quick.

Unfortunately the work on the control valve was done 3-4 years ago and I honestly can't remember exactly what I did. But... having said that I have a strong feeling that I read cautions on the board about abrasives and do not think I would have used any. More likely just a rag and diesel or petrol. I do not think I touched the unload valve at all. This may be incorrect however and also, given the state of the tractor (2 o-rings missing from both the piston assembly and flow control assembly junctions, damage to the control valve end and wrong threaded bolt in one piston assembly mounting hole - unless there is an oddie meant to be there), I'd not be surprised at the condition of anything.

Unlikely to be able to find another flow control assembly. I have new o-rings now and a piston seal on order (hopefully 2-3 days). I'm happy to reassemble and strip back if necessary. I will post results.

I managed to replace the position arm pin OK using the 5/16" drill method and a small vice, socket and bolt to push the old one out.

A couple of things. Do you know the thickness of the flow control gasket? And, does the gasket clear the o-rings or do they make contact with the gasket. I will have to cut a new one.

Is there anything I can /should check in the control/unload area while it's apart?

Also, any thoughts on the leak below the control lever? I have removed the pin and cap but the shaft (restrictor valve) gets quite stiff after a few mil. Can it be driven out OK?

The gasket is very thin, about 0.030". If it is too thick the "O" rings cannot seal. You do not have to have a gasket at all in some cases. The gasket goes round the rings not over them.

You need to take the flow control valve out before removing the shaft.

The flow control valve housing is hard to remove, is it not? How should it be removed if this proves necessary?

Thanks for further info Brian.

Still waiting for main piston seal. I've removed both the control and unload valves. All looks OK and I will fit a new o-ring to the unload valve. I was also able to remove the flow control valve and restrictor shaft without much trouble.

? There was no o-ring on top of the restrictor shaft. It looks like there should be according to the service manual. Does anyone have a spec for this? I'll use best guess if not. I'm guessing this is probably the reason for my leak in this spot.

I was trying to think what would have changed when I adjusted the hydraulics that has caused the power loss. One thing I did do was use some old silicon to seal the lift cover. It looks like my application of this may have been generous around the 2 o-rings. Could a leak in this area cause the lack of power? Is it actually necessary to seal this at all?

BTW, to remove the flow control valve plug, I tapped it in about a mil to loosen it then used a wood screw (hopefully nice and soft) to screw into the small hole in the plug and was able to withdraw it with this. I may be lucky in that it was probably not badly seized.

Thanks again for all the help.

You need an "O" ring on the flow control.

Your problem does sound like an oil leak on the pressure side. A leak on those rings could give you a problem. A little thin film of silicon is OK.

Your method of plug removal is spot on. They are not usually very tight.

Oh happy me! Finally got the lady back together yesterday and all seems to be greatly improved. Operation of the lift arms starts at about 1/4 - 1/3 through the quadrant though. Is this normal? The arms fully raise. All leaks seems to have been fixed with missing o-rings and gaskets replaced although it's early days. Lift arms seem solid in position although I've not put a huge weight on yet. They did drop slightly (2-3 inches at ball end) as I put extra weight on the tray (about 10 fence posts) but did stabilise again and I was still able to raise them fully up with the extra load on.

So, a huge thanks to Brian for your help and to all those who keep this and Stefan's site going. Last thing I need to do is recheck the fluid level. I assume it will drop a little as the system fills. Is there any problem putting in say an extra litre once the level hole is reached?