Pressure problems Primus 1020

Discussion in 'Fettling Forum' started by Peter, Jun 20, 2019.

  1. Peter

    Peter Aland Islands Subscriber

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    Hi all!

    Im restoring a Primus 1020 for a friend of mine and having problems getting it pressurized when pumping it. It will pressurize when I use compressed air instead of the pump.

    What I’ve done:
    -New NRV and gaskets.
    -New pumpleather
    -New filling cap gasket.
    -New needle
    -New graphite gaskets.

    Could it be that my new pumpleather not sealing enough to create the preassure needed to press air throug the NRV? I’ve oiled it up with motor oil before fitting it into the pump tube.

    Never had this issue with any of my P’maxes.

    Any ideas?

    /Peter
     
  2. Nils Stephenson

    Nils Stephenson Founder Member

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    Once it has pressure, does it stay pressurised? That way the problem can be localised to the pump or not. Does the leather fit snugly in the pump tube?
     
  3. george

    george United States Subscriber

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    Think Nils is right. Sometimes the new leather pump just does not seal enough to really pump it up. I take the pump plunger with the leather out of the barrel, wipe off the oil, wipe down the inside of the pump barrel, and spread the leather just a little with your fingers, reinsert the plunger and try again. Both my 1020 lanterns do not need a lot of pressure. They work great with low pressure (about 12-15 pumps).:D/:thumbup:
     
  4. Peter

    Peter Aland Islands Subscriber

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    Thanks for your replys!
    @Nils Stephenson yes it stays pressurized when I blow air in it with my compressor.
    Leather fit snug, even struggled a bit to get it in...I’ll remove the leather and wipe it dry and try again. Think I might got a spare leather to try with as well...

    Thanks again guys!

    /Peter
     
  5. Nils Stephenson

    Nils Stephenson Founder Member

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    Well at least the issue is localised to the pump. Is this a lamp that you have had working before? Do you have other Primus lamps that work? If you do, try swapping the pump.
     
  6. AussiePete

    AussiePete Australia Subscriber

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    I have had this problem quite a few times and I found that there could be 2 causes. One is that leather was/is not pliable enough, I now soak the leather in olive oil, or oil of your choice, overnight. Then I mount the leather on the pump shaft and with pointy nose pliers, work the edge of the leather all way round, actually softening the rim of the leather, re-oil it and the leather now is more able to expand and seal.
    The second cause could be that air cannot get past the leather to be then compressed on the pump stroke. I’m not familiar with your type of lamp but on others, Tilley or Coleman etc. the air, on the back stroke, enters the pump chamber through the centre of the leather and under compression, the pump stroke, the leather pushes back sealing against the backing washer. There is usually a small metal ring that keeps the leather being compressed too much by the holding nut, this ring assists in letting air past and into the chamber on the back stroke.
    When the leather appears to move to allow air in correctly, I rebuild the pump, not forgetting to freshly oil the leather. When the pump is all together, I give the pump a very fast push for the first couple of pump strokes to expand the leather.
    Hope this give you some ideas
    Cheers
    Pete
     
  7. phaedrus42

    phaedrus42 Subscriber

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    Beware of using olive oil or any other vegetable oils on pump leather. They all contain oleic acids that rot the leather and they are hygroscopic (absorb water) too. A fatal combination. Mineral oils or Neatsfoot oil will ensure longevity of the leather.
     
  8. AussiePete

    AussiePete Australia Subscriber

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    @phaedrus42 you are most likely right. I shall now change to neats foot oil. I used olive oil coz my Grandfather used to use it in the way back days. I really didn't give it any thought, thanks for the heads up.
    Cheers
    Pete
     
  9. Nils Stephenson

    Nils Stephenson Founder Member

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    For Primus, the pump leather is tightly fitted to a 'carrier' which is then loosely fitted to the pump rod. The pump rod has a narrower section where this carrier fits with a tapered section to the larger diameter. When on the compression stroke, the carrier pushes back against this taper sealing the pump and on the back stroke the carrier pulls away letting air through the centre of the carrier around the pump rod. I'll try and take some photos when I get home from work.
     
  10. MYN

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    @Peter ,
    You can check if the carrier that Nils mentioned is actually sealing against the pump shaft or not during the pushing stroke. You should be able to feel some resistance (apart from that caused by the leather against the pump tube wall) from the back pressure. Otherwise, most of air won't get pass the nrv as its leaking through the carrier/shaft again.
     
  11. Nils Stephenson

    Nils Stephenson Founder Member

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    Here are a couple of pictures of the Primus pump rod.

    Pump_assembled.jpg Pump_disassembled.jpg
     
  12. AussiePete

    AussiePete Australia Subscriber

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    Hi @Nils Stephenson I see now, I think Primus pressure stoves have a similar setup.
    Maybe @Peter has a problem in this area, coz I have seen where previous “fixer uppers” had mistakenly packed the leather cup carrier from moving back and forth on the shaft ...... rendering the pump almost useless.
     
  13. Nils Stephenson

    Nils Stephenson Founder Member

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    Yes, pretty much all Primus stuff uses the same principle (even identical parts for many). There are exceptions though, but not many.
     
  14. Peter

    Peter Aland Islands Subscriber

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    Sorted...I mounted the nuts keeping the leather wrong...](*,):oops:

    Thank you all for pointing me in the right direction!

    Keep those lanterns gloving and have a nice summer!

    /Peter
     

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