Power Major Vaccuum control unit broken?

ChrisB · Post by **ChrisB** » Fri Jun 18, 2010 4:55 pm

Got a 58 FPM and wanting to correct some surgin so have started looking at the air control diaphram end of the injector pump, the rubber seal has been replaced, but noticed that there is a small plunger like arrangement which rests on the vaccum side of the diaphram, passing through the vacuum suck and air bleed, my interteck manual discribes this an a single item with a knuckle joint, whereas what i found is in two pieces which is correct? and can it nowdays be repaired or replaced if wrong??

Thanks
Chris

super6954 · Post by **super6954** » Sat Jun 19, 2010 2:33 am

Hi Chris
This sounds like the problem i fixed on a customers tractor last year. The part you are talking about is supposed to be one peice its like a hip joint with a ball and socket. it sounds like the socket or ball is worn and the ball popped out . it then makes the tractor surge like you state. I do not know if you can get new ones. you would have to try a fuel pump repair shop. I am in Canada and we have a hard time with this stuff. I had a bad pump with good parts to fix the one I did. It ran great after that.
Regards Robert

Emiel · Post by **Emiel** » Sat Jun 19, 2010 4:03 pm

Hi,

We had the same problem some years ago. Could get the plunger back in and tick the metall sheet a little bit in so it got a little hold again. Worked for us.

Best regards

Emiel

ChrisB · Post by **ChrisB** » Mon Jun 21, 2010 10:23 am

Thanks for your comments, I managed to find a spare vaccuum unit at the weekend and it was even worse. It looks like the two parts have been apart for some time though the little piston is in good order.

Going to have a go with a center punch an see if i can join them

Many thanks
Chris

henk · Post by **henk** » Mon Jun 21, 2010 9:36 pm

ChrisB,

There are two different shapes. I know because I had a broken one to a few years ago. Wanted to put one in from another pump and notice the different.

ChrisB · Post by **ChrisB** » Tue Jun 22, 2010 1:14 pm

Many thanks Henk

looking at the picture, i guess i have had a couple of years of the little piston hitting the diaphram bolt head, mine is a touch flatter so i guess i'm going to have to try and add some metal to it !!

Anyone know if brazing would do it, i guess the union does not have to be that strong,? and i have the spare to practice with...

Alternative might be to drill deeper but that would reduce the overall length, ....could that be adjusted out ?

Chris

ChrisB · Post by **ChrisB** » Thu Jun 24, 2010 10:43 am

Fixed it.

Simple when you have the right glasses on !

noticed that where the piston sat , the shallow depression, there was a small crack, so i pushed it and discovered it was a spring loaded !! and deep!!

so used a sharp prunch with the shaft pushed fully in and it's fixed.

after 52 yrs my FPM still has a few suprises left.

Chris

BarryM · Post by **BarryM** » Thu Oct 21, 2010 7:52 am

Hi Guys,

I needed to replace the Dampening Valve on the Farm Major (Power Major Pump) and was able to purchase one without any trouble at all. A New Holland Parts Dealer obtained it for me.

henk · Post by **henk** » Thu Oct 21, 2010 6:18 pm

Barry,

Could you please give us the part number that NH is using at this moment?

Tractorbob3 · Post by **Tractorbob3** » Thu Oct 21, 2010 7:43 pm

The part shown in the photo is only half of the story! The toggle bit passes into a brass-lined externally-threaded sleeve (don't know how else to describe it) that you can see the back of, if you look on the outside dome end of the cap - it has a locknut on it. Technical term is a damping valve, I believe. Basically, the toggle piece and the sleeve are pairs and on mine, the toggle had obviously seized at an angle and had worn away the brass on one side. Consequently, as the diaphragm pushed the toggle back and forth, the wrong amount of air was getting by, so excess revs and surging was the result.

So what you need to do is to replace both parts - on some Majors, the brass sleeve was long, sticking outside the carrier and on others it was short - the difference is mentioned in the repair manual. As long as you replace as a pair, it doesn't matter. I got mine, brand new, from Peter Slater, who is very helpful, knows about Fordsons and provides a very quick delivery.

For my 62 FSM, I needed part number 84127 (toggle) and part number 82246 (guide) - I don't know whose numbers these are. All-in cost (in July this year) including delivery and VAT was just below £38 and they are excellent quality parts.

You can track him down at www.pslaterfie.co.uk - and I'm not on any kind of commission!

dennis · Post by **dennis** » Sat Oct 23, 2010 12:08 pm

Bob,

Agree with your comments about P. Slater, I also found him very helpful. I bought a diaphragm and damping valve off him.

My question is this, did you fit the nut ( Fordson Part No 33798) between the link and the small plate when you replaced your old valve with the new one. The parts list seems to suggest this is necessary.

The nut is clearly visible on the blown up diagram of the pump on page 79 of the service manual but I don't think the earlier pumps with the original diaphram and valve had one.

My new valve would not tighten fully into the link. I could not think why not so I tapped the threaded part of the link a few threads deeper. This allowed the valve to properly tighten and I re-installed the unit. Only then did I read about the nut, which would have effectively acted as a spacer, and made the extra thread depth unnecessary.

I note you changed the valve and guide but I would be very interested to hear if you, or anyone else, has had to deal with this problem. The point being that the valve takes up a different position in the guide, if the nut/spacer is missing, which may not then be sufficiently adjustable to get a stable tickover.

dennis

Tractorbob3 · Post by **Tractorbob3** » Sat Oct 23, 2010 10:20 pm

Yes - if you flip over to page 81 and look at Fig 103, the nut is clearly shown in position and paragraph 4 underneath confirms it should be fitted.

Thinking about my earlier post, where I mentioned the different versions of the guide and toggle, maybe the earlier examples did not need the locknut because they were longer?

henk · Post by **henk** » Sun Oct 24, 2010 1:23 pm

Every vacuum that I have seen so far has the locknut, but in my parts list its not shown.

dennis · Post by **dennis** » Mon Oct 25, 2010 6:53 pm

Thanks Bob and Henk for your comments,

Today, I have fitted the lock nut to my valve and am sure now that one was needed.

Henk, assuming we are looking at the same parts list, you are correct in saying that the exploded view of the injector pump (page 166) does not show the locknut but it is listed on the previous page. It is the last two notes at the bottom of page 165 that, in part, prompted my question. I will quote the notes for those who do not have the list.

*When replacing earlier type diaphram with E1ADDN 993115B, also order 33798-S7
# E1ADDN 99113B used in conjunction with E1ADDN 993115B and 33798-S7, replaces the earlier type damping valve.

993115B - diaphragm, 33798 - nut, 993113B - damping valve.

So it does appear that for a time earlier units did not have the locknut, probably for the reasons mentioned by Bob.

dennis