Doris the Dexta renovation

  1. Bill Edwards Member

    Messages:
    4,785
    Location:
    Scarborough, North Yorkshire
    Interesting. Although having fiddled and driven (round the yard) with Dexta's I know very little about them, it seems that the glow plug with fuel tap is the predecessor to the commonly found thermostart, which is a unit containing a 12v coil and fuel supply. After a few seconds of power the unit gets hot enough to open a valve to allow diesel (from a reservoir in the leakoff system) to the coil which burns and provides the heat to aid starting. It's highly effective and as it all works by just having power applied for 20-30 seconds from the heat position of an ignition switch it requires almost nothing in the way of effort* from the operator.

    *I do know at least one tractor operator (he's really a cowman) who has so little patience and sense that holding the key to just before 'start' for a full 30 seconds would be a challenge. He'd probably count to about five then open the throttle to full and just keep cranking!
     
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  2. brewdexta

    brewdexta Member

    Messages:
    3,614
    Yorkshire
    From what I have read there is a primer on the tank fuel tap that you press a couple of time, this squirts fuel onto the heater and then you press the heater button, or so the manual goes. Only really needed in winter unless the engine is tired. Also mine is one of the later super dexta's so the procedure could differ a bit. I know some get the heater going for 30 secs or so, then dump some fuel just before starting. I did buy a new fuel tap with primer about 8 years ago as the old one was not original and leaked, replacements are not cheap.
     
  3. Bill Edwards Member

    Messages:
    4,785
    Location:
    Scarborough, North Yorkshire
    I'd not like to think of giving the coil 30 seconds without fuel, I'd be worried about burning it out. Last time I counted on the thermostart units I think it was about 8 seconds to when the fuel was brought in, they get pretty hot in that time!
     
  4. armalites Member

    Messages:
    3,661
    Herefordshire
    Hi Brew, where did you get your bottles? The small one will be ideal for airline oil instead on using a the 1L bottle.

    With regards to heating the ali I've done it loads of times on Landrover wheel cylinders to get bleed nipples and fittings out with breaking them, usually a few heat/cool cycles get them out. I warm them then use the release agent to cool them, this I believe gives a capilary action which allows the the fluid to penetrate.

    I would do it with it bolted in place so that it has some structure, the key is knowing what is tight and what is stuck, that glowplug is fairly chunky so the biggest concern would be it ripping some of the ali housing out
     
  5. brewdexta

    brewdexta Member

    Messages:
    3,614
    Yorkshire
    I tested it today and your right Bill, in under 10 seconds it was glowing brightly. That was a result as it was still stuck so would have had to try some heat on it to remove it if faulty. As it is I will leave it. I masked it up and blasted it, the manifold came up well. The finish will be ideal for paint to adhere to.

    P1050822.jpg

    P1050823.jpg

    Then to check out the compressor capacity, I put a bigger nozzle on the gun and had a go at the brake back-plates. The compressor kept up with air demand very nicely. I need to spend a bit more time with the back-plate I did, this was probably after about 5 minutes or so of blasting.
    P1050824.jpg


    The small one with the metal needle tip is fleabay item number 252463650903, I bought 3 as the postage is a bit high but good for lubricating just where its needed. There's loads of the other bottles on the bay.

    Cheers
    Andy
     
  6. brewdexta

    brewdexta Member

    Messages:
    3,614
    Yorkshire
    When the tractor came out the factory, everything was sprayed empire blue in the engine bay, even the wiring. Given that I'm not after a factory finish, more a "its 50 years old and I've replaced loads of bits" finish, I'm thinking of leaving some bits bare aluminium. For example, no way am I spraying the injection pump that has just been refurbished for 300 quid empire blue. So, what to do with ali casting such as the oil and fuel filter holders to stop them getting that white crusty finish?

    I was thinking of a clear synthetic lacquer, on top of clear synthetic etch primer, both available. Could be just wax etc.

    I'm sure others have similar issues with motorbikes etc. any thoughts?

    Here's a good example of a restoration

    target engine bay.jpg

    Cheers
    Andy
     
  7. Ton-up

    Ton-up Member

    Messages:
    1,262
    Location:
    Essex, England.
    brewdexta likes this.
  8. brewdexta

    brewdexta Member

    Messages:
    3,614
    Yorkshire
    Fair comment, I have some Gibbs, simpler too. :)
     
  9. mylesdw

    mylesdw Member

    Messages:
    656
    New Zealand
    An occasional wipe and a spray with WD40 or similar?
     
  10. brewdexta

    brewdexta Member

    Messages:
    3,614
    Yorkshire
    It's been a while. The dexta came up into the upper workshop when I had no boarding on the barn below. It's now much improved downstairs and I don't want to strip all the paint and rust off in the workshop, too much dust. So down into the barn she goes ready for stripping and painting while we have the weather. It's now nestling on a pallet so I can move it around, a friend reckons he has seen the ideal trolley for the rebuild and is going to see if he can get his hands on it, if not I shall rig up a quick trolley with castors on.

    The axle goes through the hole when you turn it on the diagonal, just.

    P1070516.jpg

    I can now clean up the workshop as it was taking up loads of room, and start painting the ancillaries. I have loads of house DIY to do but will be cracking on and getting as much of this done so that next year I can enter it into a couple of local agricultural shows for a bit of fun, if you have a goal there is more chance of getting it done and this has been hanging around too long.

    Cheers
    Andy
     
    Last edited: Jun 19, 2018
  11. postie jon Member

    Messages:
    763
    Location:
    Aberdeenshire, Scotland

    dad has a dexta ,had it for 48+ years, it would be a last of the line model just before the super came out, he says it has far more poke than others he drove , basically the oil light came on once she was warm and stayed on, so he stripped it ,found the oil suction pipe had a crack in it got it braised and tried again, no joy . stripped again he checked the tolerences of the pump which was within recomendations but we persuaded him to fit a new one when he was in there ,he also got a new crankshaft , shells etc ,etc from a good farm mechanic we know. Agriline supplied the new oil pump, now once she is running up to heat its is throwing an astranomical ammount of oil out of the engine breather, so much so he has fixed a litre bottle to the end of it too catch it ,vented of course, they measured the pressure and it was way too high,cant remember actual figures but it was more than double what it should be . question is he wants too strip it again and fit the old one , me and brother are no so sure, dad has since had a stroke and cant walk or use his left arm so we would be doing the work he did the bulk of work himself ,he was 80 in february and very active on the farm ,so its now getting him down being bed ridden in hospital for the past 5 wks. so we want to keep his ole girl going ,is it worth refitting the old or stick with the new & keep topping the oil up ? yours postie J.
     
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  12. brewdexta

    brewdexta Member

    Messages:
    3,614
    Yorkshire
    Sorry to hear about your dad, mine had a stroke the year before last so know what your going though. I'm far from a Dexta expert, definitely still learning and lagging behind. There are all sorts of quirks with this tractor but help is at hand.

    I would join The Fordson Tractor pages and search the Dexta section first, if you can't find a similar problem, and I would be surprised if you didn't, then there are loads of very experienced owners on there. One guy, Brian, used to maintain Fordson's in the field. If you can't find the issue answered already, when you ask a question, the quality of the reply will depend on the quality of the details you provide so I would make sure you mention all of the symptoms, where you measured pressure, what it was etc.

    The engine is Ford's version of a Perkin's engine, quite ubiquitous, so somebody on here may be able to help too but it is still worth joining the above forum.

    Cheers
    Andy
     
  13. johnser

    johnser Member

    Messages:
    1,718
    Location:
    North Cornwall
    Is there an oil pressure regulator on these? I'd imagine so, a ball bearing held by a spring. Maybe someone has in the past tried to mask the symptoms of a rubbish oil pump by stretching the spring or putting in a bigger one.

    I wouldn't be too quick to ditch a pump that is giving too much oil flow/pressure!

    Also, I wonder why the overpressure of oil correlates to oil out of the breather?
     
  14. Ian James Member

    Messages:
    825
    Location:
    South west scotland
    Oil been blown out of the breather is usually a sign of worn piston rings meaning the compression from the cylinder is escaping past the the rings and pressurising the crank case
     
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  15. johnser

    johnser Member

    Messages:
    1,718
    Location:
    North Cornwall
    That was my thoughts. Why better oil pressure would highlight it, I'm not sure.
     
  16. Ian James Member

    Messages:
    825
    Location:
    South west scotland
    In theory better oil flow shouldn't but if it has had the crank don that will mean it has had a full strip down maybe carbon build up on the rings was preventing any blow past before
     
  17. postie jon Member

    Messages:
    763
    Location:
    Aberdeenshire, Scotland
     
  18. Ian James Member

    Messages:
    825
    Location:
    South west scotland
    @postie jon another thing to consider from reading your post above it sounds othough you fitted a new crank if this is the case if the tolerence were tight this would up the oil pressure due to the oil being forced through a tighter gap but wouldn't have anything to do with it blowing oil through the breather maybe the two problems are unrelated
     
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  19. postie jon Member

    Messages:
    763
    Location:
    Aberdeenshire, Scotland
    thanks everyone,sorry brewdexta for hijacking your post,wasnt expectn so many replies,:worms
     
    Last edited: Jun 19, 2018
    brewdexta and Ian James like this.
  20. dobbslc

    dobbslc Member

    Messages:
    3,932
    Location:
    Hertfordshire UK
    Does the oil filter have a check valve iniit on these old engines?
    Could be as simple as a duff oil filter.
    Mum had a stroke 18 months ago, she's In permanent turmoil now:(

    5 weeks isn't long so hopefully your dad will improve to the point he'll be getting in the way again! :D
     
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