123 Cap Gasket

Discussion in 'Fettling Forum' started by johneliot, Oct 2, 2016.

  1. johneliot

    johneliot Subscriber

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    I have found something interesting and I was wondering if anyone has run into the same issue. The last two 123's and one Primus 71 I have fettled has had the same issue. All 3 I have totally been broken down and cleaned but when I put them back together they have burned very poorly. As with all these stoves I know it's due to a loss of pressure as it heats. All of them I have used a cap gasket from the Fettlebox which is 10mm x 18mm. When I switch it to a .7 x 3/8 gasket they burn beautiful. I'm at a loss as to why. Not a big deal. I keep both on hand.
     
  2. shagratork

    shagratork United Kingdom Moderator, R.I.P. Subscriber

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  3. The Fettlebox Sponsor

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    @johneliot The ID won't be so critical as long as it goes over the centre valve boss as this isn't a sealing surface. The OD is more critical. 0.7" is actually smaller than the Fettlebox seals at 18mm so I don't think it's an OD/ID issue.

    Thickness could be an issue. They should be 2mm thick. Can you confirm the thickness please? It's possible I may have cut them in 1.5mm by accident but even if I have those should still be ok (I know some suppliers make them in 1.5mm as it's adequate & cheaper). I also stock 3mm & 1mm sheet - both of which would be virtually impossible for me to cut & then pack without noticing my mistake.

    You had 3 packs (6) in 2014 & 2 packs (4) last year. Any inconsistencies across the 10 washers? Do they all give the same issue?

    Another issue could be hardness. If your alternative washers are softer you may not have to tighten the cap as hard to get a good seal. The Fettlebox ones may need to be a little tighter?

    What's I'd like to do is paypal you a refund for all 5 packs & the cost of returning the problem ones to me for checking as I would like to get to the bottom of this. I will send you replacements free of charge. I've supplied thousands of these without any reported issues & have similarly used dozens myself.
     
  4. The Fettlebox Sponsor

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    @johneliot Not the thickness?

     
  5. Tony Press

    Tony Press Australia Subscriber

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    @johneliot & @The Fettlebox

    I'm not attempting to get involved in a "he said, she said" here, but I've refurbished 6 SVEA 123/123Rs, and 4 different cap/SRV arrangements.

    I've used "The Fettle Box" Viton seals and had no problems at all.

    Cheers

    Tony
     
  6. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Me, too. All the gaskets I have received from FB for the 123 style cap have been good first time every time. I have a bag clearly identified as they came from FB. I can check them if you need me to.

    @johneliot
    Have you done a dunk test after the fettle?
     
  7. johneliot

    johneliot Subscriber

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    Thanks for all the replies. First off let me say that I have 12 of these stoves. (No I don't have a problem, really!) Up until these last ones, the gaskets I have gotten here have work beautifully. I appreciate the offer for a refund, but I don't think the seals are the problem. On one I took a cap off a stove that I know was working and put it on one of the last three and it worked fine. I tried it on one of the others and it didn't work. I just posted the question to see if anyone had run into this problem. I was thinking that maybe there was a difference in the way the cap threaded on, or maybe once in a while I just pick up a persnickety stove. I will say that two of the last three were about the grubbiest stoves I have ever fettled! This will in no way keep me from getting more from our host as I think they are a superior product.
     
    Last edited: Oct 3, 2016
  8. Normo

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    Just a wild guess here... I have also used Fettlebox gaskets with no problems, but wondering if the caps are somehow mated to the stoves and you have accidentally mixed them up. Slightly different thread length perhaps?? Are some caps off a clone??
     
  9. johneliot

    johneliot Subscriber

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    No to both questions. I too think it has something to do with the threads on the fount and/or the caps. Just not sure yet as to what.
     
  10. Tony Press

    Tony Press Australia Subscriber

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    @johneliot

    John

    Check the mating surface of the filler tube and the cap. I'm in a bit of a rush, but elsewhere on this site I posted a photo of a 123 that had a big ding on the top of the tank filler tube. It required some sanding before the cap would seat properly.

    Cheers

    Tony
     
    Last edited: Oct 4, 2016
  11. Etherman

    Etherman Subscriber

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    Would it be worth testing the cap on say a 111 where you can put pressure on the cap then leak test with dunk or liquid soap to confirm or rule out the cap seal is why your loosing pressure?
     
  12. johneliot

    johneliot Subscriber

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    Tony, I'll check the last stove around the fill tube and see if I can feel any dinks or pitting. Etherman, when these guys don't hold pressure after replacing the gasket, I always do the dunk test. Most times I get a slow bubble out of the cap and at that time I'll replace the pip. The last one I had to dig it out. I re-dunk to make sure it's no longer leaking.

    John
     
  13. The Fettlebox Sponsor

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    Just to be on the safe side I'll pop 3 fresh seals in the post for you. I'll put 3 srv pips in too. Keep us posted on how you get on.
     
  14. snwcmpr

    snwcmpr SotM Winner Subscriber

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    So how do you know there's a problem? Are they blowing bubbles?
     
  15. sa3spd

    sa3spd United States Subscriber

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    Hi,

    Stupid question for John: when you installed the new gaskets in the caps, did you also put in fresh SRV pips? I would assume you did, but perhaps that slipped by. I ask from personal experience--I'd installed brand new FB Viton gaskets in a couple of caps and was still losing pressure! Oops...

    Rick C
     
  16. johneliot

    johneliot Subscriber

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    Ken, that actually is what's got me confused. When I dunk again, I don't see any bubbles but it still doesn't burn until I use the lower quality gasket. I have an idea I'm going to try this weekend. I'll let you know if my guess is right.
    Rick, when the gasket doesn't cure the problem or if I get a slow bubble out of the cap when I dunk it, I replace the pip. The last 2 out of 3 stoves I've had to do this.

    John
     
  17. snwcmpr

    snwcmpr SotM Winner Subscriber

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    So, if it passes the dunk test, it's not likely to be the seal.

    A test I use. When the stove is running, I wave a torch across the tank. Just to make it warmer. I want to know if pressure helps it burn. If it does improve the flame I will let it burn for a long time, several tanks to clean or I will change/check the wick.
     
  18. johneliot

    johneliot Subscriber

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    Well, here's what I think is happening with the couple of stoves I had gasket issues with. I think Tony was on to something. I rechecked the two I had issues with and they both had some imperfections where the cap met the filler tube. I used some wet/dry paper to smooth it as much as I could. I also screwed the cap on as tight as I could get it by hand and let it compress the Fettlebox gasket for a couple of days. Both of those items seems to have fixed any issues. The other gaskets are thinner and I'm of the mind that they formed sooner over the imperfections than the thicker ones. All is well. Thanks for all the brain storming!

    John