Mewa 351

Discussion in 'Fettling Forum' started by Scott D, Apr 30, 2021.

  1. Scott D

    Scott D United Kingdom Subscriber

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    Good morning all,

    I’ve just managed to snap the cleaning needle rod in the Mewa 351. I’ve been searching for a supplier but not found one yet. Are these out there or will it need a repair?

    Thanks

    Scott
     
  2. WimVe

    WimVe Subscriber

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    Well these lanterns are not made anymore for a long time so finding a supplier is not easy.
    Best and fastest way is repair it.
    Long way: find a donor lantern.
     
  3. Scott D

    Scott D United Kingdom Subscriber

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    Thank you
     
  4. Scott D

    Scott D United Kingdom Subscriber

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    Making some progress with the Mewa, maybe. Solved the snapped cleaning needle issue using an electrical copper crimping ferrule which seems to be working well. Got it back together for a test run before stripping it down again for final clean and fount spray. However I have been fault finding for weeks on it, 10 mins at a time, as it would light albeit reluctantly run for a couple of minutes before just dying out as though it lost pressure. So I’ve checked every seal, sprayed with soapy water but found nothing, no leaks at all. Before resorting to a dunk test I had a recollection of reading a debate about what fuel these run on and wondered if it could be a burn temp issue. This is getting to the limits of my experience now though. Given the lack of a fuel shut off and a spirit cup for preheating I have been trying to use paraffin. So I put a good slosh of holts brake cleaner in the fount in addition to the paraffin (probably making it no more than 1:10) and it has now been running well for about 30 mins. I’ve read with interest about blended fuels but had no reason to try it until now. My questions are, firstly is it safe to run in a lantern with no shut off? It would only ever be used outside anyway. Secondly, if I can get away with a blend then does anyone have any recommendations on best ratio? I assume not too high if I’m venting the fount to extinguish the lantern.

    Thanks

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  5. Henry Plews

    Henry Plews Subscriber

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    As long as you don't increase volatility too much, your lantern will be safe to use.

    Of the lanterns I have which work best with blended fuel, I've found that 5% has little noticeable effect, 10% improves the burn for most though I have one which prefers 15% and one runs sweetest with 20% more volatile fuel added but that does have a positive shut-off valve and needs a separate pump to pressurize the tank. There is no improvement when more than 20% is added.
    In summary based on my own experience, between 10 and 15% seems to work best in most instances and more than 20% doesn't improve performance. Don't be afraid to experiment a little to find the ratio which best suits your lantern and remember that it's not just about brightness, you may find that a lamp burns just as brightly by adding 10% of whatever as it does when you add 15% but you may have to use the cleaning needle more often.
     
  6. Scott D

    Scott D United Kingdom Subscriber

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    Thanks @Henry Plews, so this was purely an issue with operating temperature sustaining the burn sufficiently? I was getting really frustrated, the flame looked just like it was losing pressure but there were no leaks and still had good pressure in the fount. It is really interesting, just as I think I’m getting the hang of these systems something new comes along!
     
  7. Martin K.

    Martin K. Subscriber

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    @Scott D Have you investigated whether the fuel pickup tube in the fount could be broken/cracked? I have experienced that not only once, and the symptomps are a pressure loss while the dunk test always shows no problem. The reason is that air in the tank rather than only the fuel can escape through the vaporizer, but depending on the size of the leak you will only notice that after a few minutes or even 1/2 hour, as you said.
    Regards, Martin
     
  8. Scott D

    Scott D United Kingdom Subscriber

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    Thanks Martin, that’s one to bear in mind. Pickup tube looks to be ok and since starting to use a blended fuel it seems to run ok now. It’s all stripped down again now for painting. Primer done today actually, just debating whether to apply body filler to address the pitting in the steel. The primer has taken the edge off it already though so I think it will be ok.

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