Dexta Hydraulics still bleeding off !!!

[jwhiteker]

I have inherited a 1958 Dexta in decent running condition. My issue is that it's used predominantly for mowing with a bush hog and the hydraulics keep bleeding off. I've had the top cover off several times. I've replaced the o-rings including the one on the piston. Everything looks to be in good order. I took it to an old timer who's supposedly good with these old tractors. He found that my external top link was too tight and adjusted it. He then hooked up a pressure gauge and said it was pumping within spec and holding well. Once I got the tractor back home and started mowing, the bush hog once again started dropping as I mowed. Within 100 feet of mowing, my bush hog is scalping the grass. I've changed the oil to 90 wt. trying to get a more solid hold as per the mechanic's recommendation and that didn't help either. My mechanical and tractor skills are pretty solid in my opinion, but I'm completely stumped. Does anyone have any ideas of what I should try next? I could try to adjust the internals, but good luck finding the special gauge tools offered by Ford and Fordson back in the day. I also cannot get any Ford dealership in the area to work on something this old. It's all on me. Any help would be extremely appreciated.

[Brian]

Two things, give us an idea of where in the world you are as there may be someone near you who can help.

Drain the 90W oil and refill with the correct grade of either Multiuse/Multipurpose or 30W. Fords found in 1958 that heavy oil like 90W would not flow through the tiny holes and drillings in the lift.

The lift drops because it has an oil leak, nothing to do with the hydraulic pump. You have already replaced the piston seal but did you use the "cupped" seal or an "O" ring as supplied by some after market suppliers? You really need the "cupped" seal.

The other areas that could be leaking are, control valve, unload valve plug, check valve or ram cylinder safety valve.

Lift the lift to full height, pull out the Auxiliary Service Control knob and see how long the lift takes to drop. If it holds up, your problem is control valve, unload valve plug or check valve. If it still drops your problem is piston seal, ram cylinder safety valve or "O" rings on the ram cylinder or Auxiliary Service chest.

No need for the Ford special tools to reset the lift. Find your way to the Wiki on this site from the forum heading, use the words "fordsontractorpages" and the password "dotty" to get on to it and you will find an article on setting up your lift without the special tools.

[jwhiteker]

Thanks you Brian. I live in Andover, KS just east of Wichita. My tractor lives just north of Fall River, KS which makes things even more difficult. I am only able to make the 1 hour drive on the weekends to mow and lately... work on the tractor. Anyhow, my auxiliary service control knob has been stuck for 30 years so I cannot pull it out. The plastic knob is actually missing but I do have the nub sticking out. I may be able to get vise grips on it and pull it out possibly. I just haven't ever done it for fear of breaking the valve internally and such, but I will try. And I will eventually switch to the lighter oil but I know this isn't my main issue. It ran for quite some time with no issues and at that time it actually had hydraulic oil in the case. And lastly, I will try to navigate to the Wiki you mentioned and see if the information there will help me with correct adjustments. I appreciate it.

[Brian]

So it is no good suggesting that you put the lift in the boot of your car and bring it to me to look at as DWD did over the weekend

It is a bit of a problem if you cannot diagnose your problem as suggested, the other way would be to pressurise the lift with air and see if you can find the leaks.

Ask what questions you like and we will try and help.

[jwhiteker]

Yeah Brian, while I would love to have an excuse to throw my lift into a suitcase and cross the pond, it would probably be cheaper for me to just replace my old blue girl with something from this century and from this continent. I will be making the trek out to the farm this weekend and I will hopefully find time to tear back into it. The adjustment guide on the wiki is somewhat deep, but I think I understand what I need to do. I will do my best to bring back good news or at least more information for the gurus on this forum. Thank you so much.

[Brian]

Had a thought this afternoon as I was doing some topping. Are you in Position Control? That is with the little selector lever near the quadrant pointing straight forward. She should hold the arms at that position set by the quadrant lever and return to it if it drops below the setting.

[jwhiteker]

Update: Ok... yes Brian, I am operating in position control, not draft control. I actually made it out to the farm this weekend, but with the crazy amounts of rain we've had this spring I had to spend my time trying to mow instead of having time to work on the tractor much. I did make some headway though. If I get my implement into position and pull the auxiliary knob to the full "out" position, my lift arms stop bleeding off and I can cut grass indefinitely without it dropping. I realize this is not a fix and it's somewhat of a handful if I come to a place where I need to raise the mower up quickly, but it served me well this weekend for my mowing purposes. I will have to look back in my service manual to see what this points to. I remember seeing that this was one of the possible tests to narrow down the problem. Slowly but surely we'll get this thing done!