Stuck NRV, what else to do?

Discussion in 'Fettling Forum' started by Sternenlicht, Jul 15, 2020.

  1. Sternenlicht

    Sternenlicht Subscriber

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    Hej everybody,

    The NRV in my Primus No.1 Old Primus 1 DRP, which date? stuck.

    I tried boiling water in the tank, penetrating oil, soft hammering with a hammer on the nrv tool. I also build a new nrv tool which sits quite narrow on the nrv.

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    But nothing works.

    Are there any other things I can try?
    Removing the complete pump tube should be the last step... which I have never done before :o

    Ciao, Bastian
     
  2. nmp

    nmp United Kingdom SotM Winner Subscriber

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    @Sternenlicht
    Try plus gas releasing oil down the pump tube and apply pressure to the pump rod but not enough to open the NRV it might force some fluid into the thread? Boiling water does help sometimes but not always.
    Make a NRV tool that is held onto the head of the NRV using a pump tube cap so it cannot twist up and off of the NRV as you apply force?

    your home made NRV tool looks very good by the way.

    Freeze the tube then pour in boiling water? Anything to try and break the initial seal.
    Removing the tube on an old lady like that should as you say be a last resort!

    Good luck Nick
     
  3. mr optimus

    mr optimus Subscriber

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    Hi Ciao you may well have to remove the pump, could try again with the penetrating oil leaving it over night, and try tightening it and then try undoing it this mite break the seal
     
  4. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    What’s the condition of the NRV head? I think you’re saying that the screw threads just don’t give way, not that the NRV tool rotates on damaged NRV head flats?

    What works for me is to clamp the NRV tool vertically in a vice and engaging the tool on the NRV and gripping the fuel tank firmly in the hands, turn the fuel tank on the tool.

    The worst that can happen is that the tool ‘cams’ over the NRV flats or - if it were a Burmos but probably not a Primus - the solder of the end cap shears. Either worst case scenario would require removal of the pump tube, which was where you were heading anyway.

    John
     
  5. igh371

    igh371 SotM Winner Subscriber

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    or you put so much pressure on through the tank to prevent the tool riding up the NRV head that you crush in the whole tank side:oops: … in which case removing the pump from the tank would seem in retrospect to have been the better option.
     
  6. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @igh371 Heck, Ian. I wasn’t advocating force of that magnitude! No ‘downward’ force to speak of, merely more, and more controlled, application of torque to the NRV. Try it, you’ll warm to the technique.

    John
     
  7. The Warrior

    The Warrior United States Subscriber

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    I couldn't get the NRV out of my Primus 210. Soaked it in oil for a month, and it still wouldn't budge. I read somewhere that if you tighten it a bit first, before trying to undo it, it would come out. That trick worked for me. Primus 210 Fettle
     
  8. igh371

    igh371 SotM Winner Subscriber

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    Only with extreme caution - in the past I've stove in at least 2 tank sides using that approach - the 'blushing face' smiley wasn't there for nothing:oops::oops::oops:

    (also torn the complete head off an NRV without the thread budging - it took a really good quality NRV tool to achieve that:roll:)
     
    Last edited: Jul 15, 2020
  9. Sternenlicht

    Sternenlicht Subscriber

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    Dear all,
    so many helpful advices... thanks a lot!


    @nmp
    These things I will try first. A damage of the nrv is unlikely to happen.

    @mr optimus and @The Warrior
    I forgot this technique, I used that in other cases, but not for stoves, I will try that.

    @presscall
    I read about 'your' technique before and also tried that. But I had fear, the nrv will break, as already happened with two other stoves. But in both stoves the nrv have been much corroded. It has bern a lot of work to get out the remaining part.

    The nrv head is still ok, I only grinded off once. That was the reason for me to make a better nrv tool.


    I think the main problem is the missing lead washer. Due to corrosion and strong force for tightening the threads don't give way.

    I will make a little break and turn on the comming days.

    Ciao, Bastian
     
  10. snwcmpr

    snwcmpr Subscriber

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    How much time has passed?

    My experience with this has been the techniques mentioned.... but the use of patience and penetrating oil. Weeks not hours.
    I always keep a good dose of patience in my toolbox for times like this.
     
  11. threedots New Zealand

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    Hello @Sternenlicht .

    I looked at your Primus DRP in your first post about it and can see that it is covered in hardened kerosene shellac runs. That shellac can be dissolved with alcohol.
    :-k I wonder if your NRV threads have hardened shellac around them, acting like Thread-lock and locking your NRV in place?

    When reviving older stoves, I like to fill them with methylated spirits first to dissolve any shellac type residues that may be inside the tank, burner, NRV and jet threads. I let the filled stove stand for a week or more if needed with an occasional shaking during that period. Then empty and flush with fresh methylated spirits and air. I find using that process helps when removing old crud and stuck NRVs. John
     
  12. Radler Switzerland

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    @Sternenlicht
    You have made a good NRV tool.
    To modify it to a non-slip tool, with a ¼" drive, would be quite easy. All you need is a file and a vice.

    The advantage is, the tool does not need any force to keep it in place. All force you apply is torque, no force which pushes the NRV more on its seat, instead of moving it out.

    I invented this tool for a similar old stove. It was not possible to move the NRV with all other tricks until I made this tool. Then it was very easy to remove the NRV, without deforming it.
    Making a special key for NRV removal

    Radler
     
  13. Sternenlicht

    Sternenlicht Subscriber

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    Hej @threedots
    I cleaned the inner and outer stove already with acetone. I dont think that there is hsrdened kerosene at the nrv anymore.

    @Radler
    Cool! I didn't know that thread, thanks! I will modify my tool also.

    @snwcmpr
    You are right, but patience is hard to learn sometimes...

    Ciao, Bastian
     
  14. Harder D. Soerensen

    Harder D. Soerensen Denmark Subscriber

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  15. Twoberth

    Twoberth United Kingdom Subscriber

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    @Sternenlicht
    I can recommend Radler’s non-slip NVR removal tool.
    I have also used all the items in Harder’s general tool kit!:lol::lol:
     
  16. Majicwrench

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    I don't believe penetrating oil helps in these situations....if it could seep through the threads so would the pressurized kero in the other direction. Penetrating oil, however, is not going to hurt, so might as well try it.

    Lots of good advise. Not having worked on a ton of these I humbly offer my one "stuck" experience, I finally pointed my propane torch down the hole for a couple seconds, fully realizing I could melt all the solder. But it worked, NRV popped loose easily after that.
     
  17. snwcmpr

    snwcmpr Subscriber

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    That was probably after days of penetrating oil, and loosening it many times before. :)
    Hat and coat... on the way out.
     
  18. Harder D. Soerensen

    Harder D. Soerensen Denmark Subscriber

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    In agony over a stuck NRV - after letting it soak and working on it for days - I heated my homemade tool and placed it over the NRV - with the result, that the bottom of the pump tube with the NRV fell down into the fount.
    Oh well.....
     
  19. Sternenlicht

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    Hej everybody,

    I got the nrv out!!!
    I soaked it in penetrating oil for several days. After that I filled crushed ice into the pump tube, removed the ice after a few minutes, filled in boiling water... I repeated that three times. Then I wrapped my nrv tool with tape for a perfect fit and screwed out the nrv without any force. Cool!!!

    The stove was cleaned with hot water and acetone only, I relaced the original cork pip against one from viton. The original jet was worn, I changed it first against a to small jet, I guess 0.28mm. I drilled it to 0.32mm. The pump leather and the seal in the filler lid are still original. On that seal you can recognize the word 'PRIMUS'.

    Thank you all for the great help and advices!

    Ciao, Bastian

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  20. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi, Great result and a fine flame-pattern from your newly fettled Primus No.1 stove.
    Best Regards,
    Kerophile.