The Fordson Tractor Pages Forum

Hello folks,
I've just registered so new here but am an avid E1A fan, however I am having a testing time with '63 NP Super hydraulics which have been bobbing when carrying an implement. By that I mean Bob every 3 - 5 seconds! I have had lid off, new seal on piston, new O rings between cylinder housing and lid, refurbished and re set linkage, Auxiliary service plate has previously had new O rings and gasket, new return filter, mesh filter all clean and new oil but she still Bob's. However, a second issue has occurred where she stopped bobbing but remained in constant pump when the implement is raised?? I have a replacement Check Valve to fit yet but was after sdvice on what may have happened or which other valve may be affected please?

Hi Charlie and welcome to the forum.

The TPL resetting is a natural thing I believe for the majors with draft control but the frequency may be a little high from what you say, I've a Mk2 so no direct draft control experience but this issue has been discussed a number of times and while waiting for someone who has been through this to come along, put super and hydraulics in the little white box top right of this page and press search, this will bring up a long list of topics including these words and you can read the relevant ones and learn more about it.

If you set the valve for fixed depth and the arms lift with normal force and stay there, I suspect the pressure relief valve is likely to be OK.

Hope that gets you moving for a start

Hi Rick,
Thanks for the help, I've had a read through various posts but nothing quite answers my Q's. I know it will be something simple at the end of the day, it always is with Majors, but I've not had this much trouble with my others! Thanks, Charlie

....a little more information.... when I last had the lid off and having studied the workshop manuals, I had raised an implement up on the lift, switched engine off and watched what happened - sure enough she crept all the way down to the ground. This indicates piston seal, cylinder safety valve or Check valve according to the books? I've renewed the first two with no affect so I have now got a new Check valve seat etc to fit as a replacement but in the mean time she suddenly stopped bobbing and remained in constant pump mode with an implement lifted..... something not covered in the books! Has anyone encountered this or know what may have happened?? Many thanks

Have a look at this page. Scroll halfway down to find the subject.
Sounds very much like a leaking unloading valve plug.
Best, Adrian.

http://www.fordsontractorpages.nl/phpbb ... lug#p46394

Hi Adrian,
Many thanks for your post and that does make sense, I'm in the stages of dismantling the cylinder housing so I will examine that area thoroughly and purchase some Loctite 603! Thanks again

An eyeball inspection won't reveal the issue as the plug will still be a very tight fit even though it is leaking.
Once you've removed the plug, check to see if the valve moves freely in its bore. It will probably have an O ring. Brian advises that this can be removed, which I was going to do, but didn't in the end.
The 603 sets anaerobically, so any excess that escapes the joint won't do any harm.
Best, Adrian.

The o ring can be removed and renewed I take it? I've pulled the "Delrin" seat and valve seat out now so I'll clean the bore up before fitting the new replacement Check Valve then have a look at the unloading valve and plug. Many thanks

So that might be the problem on my lift also. As the hydraulics are have almost a continuing "bobbing" sound. That means there is somewhere a major leak.
Adrian, how did you find out the leak was on this plug?

I'm going to confuse everybody!
Brian told me, but it wasn't our Brian. A semi-retired fitter at my local Ernest Doe outlet, also called Brian, worked on Majors and Dextas as a young man. He also studied at Boreham House, as our Brian did. Brian set up my hydraulics after the rebuild, and he checked for and spotted the excessive number of corrections (bobbing) with a plough attached and raised. He told me that it would be the unloading valve plug leaking. In service, the fix was to fit a new plug of a slighly larger size. These days we have Loctite, so I tried this, and it worked, as the technicians at Loctite assured me it would, if I used the correct compound ie 603.
The nature of the hydraulics are such that you will always get some corrections, as you get small leaks here and there. I forget what it says in the manual, but there is an ideal number of corrections to aim for over, say, two minutes. Please see my video in the link above. You can hear the desired level of corrections in the video.
End of long-winded story!
Best, Adrian.

Well I finally got back to my hydraulics and given the advice I dismantled the unloading valve. The plug certainly showed signs of scoring around the edges and the valve itself had had the O ring removed completely. I debated and opted to fit a replacement at the risk of a sticking valve.... but we'll see! She seems a good smooth fit. I replaced the plug using the Loctite 603 compound and kept my fingers crossed. I had also previously purchased a complete replacement Check Valve assembly so I was determined that too would be installed! That was relatively straight forward once I had made my own puller (Check valve seat and Unloading valve plug are both threaded 3/8 UNF). Rebuilt the lid and refitted it a few days later.... and?? It seems to have cured the Bobbing issue!! Perhaps the Unloading valve plug repair alone may have cured it but I thought I'd do it all while I was there. Many thanks for the help from you guys!

Hi,

I am trying to access the unloading valve on my 1962 super major, and would like to conform the thread size and type of the hole in the unloading valve plug. I have tried a 3/8" UNF bolt but it binds after about 1 turn and will damage the thread if I force it. Any help would be appreciated.

Thanks,

Michael.

This is a message for AdrianNPMajor
Hello Adrian,
I have been reading a post of yours dated August 11th 2011 about Super Major Hydraulics bobbing, and you speak about a semie retired fitter named Brian who worked for a Brench of Ernest Doe. I would like to trace him if I could because I have two super np's and both have this problem and it seems to baffle everybody round here, Could you please tell me what Branch of Doe's Brian worked at. I would deem it a great favour if you would,


Kind regards
Peter