Can't remove nrv (Primus 991)

Discussion in 'Fettling Forum' started by Dom182, Oct 22, 2013.

  1. Dom182

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    It's stuck tight and it's beginning to round off, any tips?
     
  2. norf

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    Which lamp? there's a lot of different NRV's
     
  3. Dom182

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    Primus 991
     
  4. norf

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    Hi,
    Thats the type with the 'raised' slot rather than the screwdriver type isn't it,,Not sure if Stu makes a tool for these which is better than the makers type ,hopefully he'll post a reply
     
  5. Carlsson

    Carlsson Sweden Admin/Founder Member

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    Dom, I take it by this that you did perform the "water dunking test" discussed earlier, and found out that it was the NRV that leaked?

    Did you also try the cleaning thingy I described there?
    It's surprisingly how often that will remedy a tiny leak.

    How did the tool look that you made for removal?

    If you made one like the one I described in the link I posted, you should be fine (unless the NRV wasn't damaged before you started). But it's very important that the slot is a snug fit to the brass head of the NRV. Once it start to slip, you're pretty much screwed since the slightest deformation of the head makes it hard to get the tool to get a good grip.
    After that you'll need a real tool, i.e. the one that has a retainer which uses the threads of the pump tube to press the tool firmly down on the NRV as you twist it.
    Last resort is to de-solder the pump tube.
     
  6. Dom182

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    Yeah I made one from some 12mm steel rod with a 5mm slot but it is so tight the bras has begun to deform so I left is soaking in wd 40 and I was thinking of warming it if I can to release any gummed up paraffin. Otherwise a proper tool job or get soldering I suppose. Where do I get a tool?
     
  7. Tive

    Tive Sweden Subscriber

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    Hi Guys,

    I use a socket extension, cut in the socket end, by a grinder, that makes a cut roughly the size of the NRV peg, then i can use the normal snap-on handle, the one time this failed, i drilled the NRV out with a very long drill of the same size as the Non threaded part of the NRV ( roughly ) it worked fine.
    Frederik
     
  8. Carlsson

    Carlsson Sweden Admin/Founder Member

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    When drilling out stubborn stuff, I try to use a drill that cut and rotate the wrong way.
    Sometimes you get the stubborn item out on the bargain.

    Dom, those tools with a hold down lid are very rare original pieces. It's not something you can buy without a big portion of good luck.
    All other tools are just the same as the ones you made your self. Only in different appearances.
    But you should have used a rod with a diameter the same as the pump tube so it would have been steered perfectly in place. Can be fixed with regular tape to thicken the one you have, though.

    I must ask again: So the thing with pressing a pump tube full of paraffin through the NRV didn't help then?
    Reason why I'm nagging on about this is that I have seen people changing NRV's just for the sake of it, or when this little trick actually worked.
    So un-necessary if it will mean a lot of work or a even ruptured pump tube.
     
    Last edited by a moderator: Mar 31, 2017
  9. James

    James Subscriber

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    Is it much harder to remove and replace the pump tube on a lantern compared to a stove? I've done it a few times on stoves and it's pretty straightforward but I've never had to do it on a lantern.
     
  10. Carlsson

    Carlsson Sweden Admin/Founder Member

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    It's just as easy. Actually a lantern generally is even easier than a stove since you don't need to protect the legs soldering from melting.

    No big deal, but it's always nice to not be forced to do it.
     
  11. Dom182

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    So fill pump tube with paraffin? The wd40 I put in drained straight into the lamp quite quickly
     
  12. Dom182

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    Well i ignored it for the best part of a week and soaked it in wd40 and it's out albeit a bit malformed. I can decide what it's meant to have in it having separated the two halves. There was a crumbly washer that seemed to be leather but the spring must be jammed up inside. Any help appreciated or can these be bought to replace it as it's damaged, I bonny fancy putting it back it with a damaged head.
     
  13. Carlsson

    Carlsson Sweden Admin/Founder Member

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    Well done. It's always a relief to get those extra stubborn ones out.
    I wouldn't put that one back. Get a new one.
    They are everywhere. It's the same used in practically all Swedish lamps and stoves. I think Base-Camp has them, and so is Fogas and probably hytta.de too.
    Or you can just simply search eBay for e.g. primus pump valve, stove non return valve or similar (stoves are more abundant, that's why I choose that word, but use your own imagination).
     
  14. Dom182

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    I've got it lit! I've used epdm rubber to make temporary gaskets and finally got the scruffy little thing going. Only thing is i'm not sure of the correct lighting procedure. I've pumped 20x then filled the meths tray full and lit it but even with many more pumps i'm currently only getting a dim orange glow not bright white? Any tips, dirty jet?
     
  15. Dom182

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    Cleaned the jet with a wire brush bristle but now I can't stop the mantle producing flames
     
  16. David Shouksmith

    David Shouksmith India Founder Member

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    Probably just as well because EPDM rubber has poor hydrocarbon resistance - it's not compatible with gasoline and kerosene for example. You need as a minimum, good quality nitrile rubber and preferably Viton...
     
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  17. Carlsson

    Carlsson Sweden Admin/Founder Member

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    You can't do it like that.
    You shall never start to pump before the preheating meths is just about to expire.
    Even if you have the cleaning needle raised to a full stop, it's seldom enough to seal off the jet completely, and that is not the intention of it either.

    Cup full of meths. To the brim.
    Air release screw opened.
    Light it and wait.
    When you see that it soon is about to go out, close the air screw and start to pump (needle down, of course).
    The mantle shall light up, and when the last flickering remains of meths has expired just pump it up until you have a good light.

    By this statement, I take it that your real cleaning needle in the vapouriser is broken?
     
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  18. Dom182

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    I did find the correct lighting procedure and it starts a lot better but I still get flames around the mantle before I get a good white glow.

    Yeah the cleaning needle is broken, another thing to go on the list of parts needed.
     
  19. Nils Stephenson

    Nils Stephenson Founder Member

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    I would guess that the wire you used was too big and has enlarged the hole in the jet. This will give you flames around the mantle. A cleaning needle for a 200cp jet should be no more than 0.16mm.
     
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  20. Carlsson

    Carlsson Sweden Admin/Founder Member

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    I'm with Nils. It sounds like an enlarged jet.
    The 991 design is so simple, and problems are practically always related to a worn jet on those.
    That is as long as the normal procedures has been performed before, i.e cleaning the mixing tube and de-coking/clean the vaporiser if needed, which is very straightforward on these.

    But you actually say that you get the flames before you get the bright white light!
    Does this mean that it will light good after a while?
    In that case it's just simply not preheating good enough.
    I guess you use a full cup, and wait as long as possible before starting the lantern?
    A full cup shall be sufficient as long as you're not in very cold conditions.
     
  21. Dom182

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    I think for certain it is because of my impatience cleaning the jet. Thanks for all your advice
     

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