Primus nickel 71, I'm at a loss. Of pressure

Discussion in 'Fettling Forum' started by hikerduane, Dec 9, 2019.

  1. hikerduane

    hikerduane Subscriber

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    Been going crazy fettling my recent buy, Primus 71 in nickel from the mid 30's. Replaced the wick, there was a "cap" of brass screen above the old wick, changed the wock position a couple times, removed material from the wick, poked the vaporizer to clear carbon out, then heated the vaporizer a couple times and got a bunch of carbon out each time, left that brass mesh cap out. Replaced the nipple, cleaned the spindle and added graphite tape. Poked the nipples many times with the pricker. Everything helped, but more scenarios the next time. Dunked the frozen fount in hot water, no leaks, then today dried the fuel out and repeated the dunk. No bubbles with a dry tank which should have only spewed air if a leak was present. Runs good for a bit of double primed. Is nickel more susceptible to a cold workbench than bare brass?
    Sorry to bother, I try not to post much.
    Duane
     
  2. snwcmpr

    snwcmpr Subscriber

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    You do not say that you replaced the cap seal.
    How long do you keep it in hot water?
     
  3. hikerduane

    hikerduane Subscriber

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    New cap washer, graphite paste added to threads on vaporizer. Placed in hot water for 30 seconds or so, plenty enough time to open the valve and see if any leak around the spindle and nut. Maybe when primed, the heat from that distorts metal.
    Yesterday, the stove spewed raw fuel after running a bit and then losing pressure. Crazy things. Fount gets very warm, so good thermal feedback. Got me puzzled.
    Duane
     
  4. hikerduane

    hikerduane Subscriber

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    Looks fairly good when pressure is at the start.
    Duane
    IMG_5746.JPG
    IMG_5744.JPG IMG_5741.JPG
     
  5. snwcmpr

    snwcmpr Subscriber

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    Aw, where did it leak?
     
  6. hikerduane

    hikerduane Subscriber

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    Not fixed, just what it can do when double primed. Ran well enough yesterday to heat up a half pot of cold water before losing too much pressure.
    Duane
     
  7. theyellowdog

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    Have you tried wrapping the brass mesh around the wick?
     
  8. itchy

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    @hikerduane

    Very strange. Do you have another 71, or something similar enough that you can swap parts and test it that way? (fuel cap, bell, perhaps vaporizer)

    Wish I had a good idea but I trust you are going to figure it out.
     
  9. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @hikerduane
    You’ve been thorough Duane, but perhaps immerse the stove in warm water, to above the depth of the valve, immediately after shutting the valve while the stove’s been running as you pictured it. Check for bubbles.

    John
     
  10. hikerduane

    hikerduane Subscriber

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    I'm thinking the only other thing I could do is double prime in my house, then dunk in hot water while it is running to see if leaking around the spindle or elsewhere.
    Before I added graphite to the spindle, there was a brief flame there, but went away after 5 seconds or so.
    John, can try your method too. Only looses pressure when heated beyond what hot water can do, but maybe priming expands metal more, then allowing pressure loss.
    Thank you guys.
    Duane
     
  11. Marc

    Marc Subscriber

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    How about soapy water while running? Look for bubbles?
     
  12. Marc

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    You say it spews raw fuel, is that out the jet, unvaporized, or elsewhere?
     
  13. snwcmpr

    snwcmpr Subscriber

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    Duane, where did the fuel leak out?
     
    Last edited: Dec 10, 2019
  14. Marc

    Marc Subscriber

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    ????
     
  15. hikerduane

    hikerduane Subscriber

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    It spewed raw fuel once out the nipple after running a bit, a few other times only a little came out when pressure ran out. That's why I say I get so many scenarios. Issue seems to be just pressure loss now. Fount was very warm yesterday, so is getting thermal feedback.
    Duane
     
  16. snwcmpr

    snwcmpr Subscriber

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    Have you run multiple tanks of fuel through it to clean the pipes?
    Have you used Seafoam?
    Have you disassembled and torched the vaporizer to smoke all the deposits out of there? I would not quench as it might crack it.

    The raw fuel out of the nipple was while burning? That would be after the flame was dying down, right? So, a result rather than a symptom.

    I say you have a pressure leak when it is hot and need to keep trying methods to id the leak. A stress crack?
     
  17. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @hikerduane said,
    I was thinking more that the pressure in the font would be greater then than just thermal expansion of the airspace vapour due to a hot water dunk.
    Might be difficult though to distinguish between air leak bubbles and bubbles caused by evaporation of the soapy water on hot components, especially the valve spindle.
     
  18. dwarfnebula

    dwarfnebula United States Subscriber

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    If you have access to an air compressor you could remove the jet, open the valve and use a rubber tipped blower down the jet hole, while immersed in water. I’d probably try to regulate the pressure down to maybe less than 35 psi? I’m guessing about pressure but I definitely wouldn’t put 90 psi to it. Anyway that’s how I pressure test 123’s.
     
  19. hikerduane

    hikerduane Subscriber

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    John,
    I was thinking priming expands any cracks, whereas a dunk test reduces metal expansion vs effects of priming. Might have caused a separation between the vaporizer and the brass pickup when I heated the vaporizer with my torch, thats when I used the paste on the threads to eliminate a possible leak thru the threads.

    Like I said, different scenarios thrown my way.
    Not my first rodeo, you may need to read my first couple posts.
    Duane
     
  20. Marc

    Marc Subscriber

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    @presscall My ignorance of the 71 showing, I'm not familiar with how hot it gets in operation.