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Svea 123 pulsing

Discussion in 'Fettling Forum' started by Jim Brizzolara, Jan 10, 2017.

  1. Jim Brizzolara United States

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    Hello, this is Jim from Grand Rapids, Michigan, USA and this is my first post. I'm an avid Coleman stove and lantern collector, and happened upon a used 123 that I couldn't pass up. This stove is new territory for me. I dis-assembled the stove and cleaned everything up, except for the NRV on the fuel cap. I also made a new fuel cap gasket out of Viton.
    The stove fired right up after a proper preheat, but even after 10 minutes of burning there's a noticeable pulse to the flame, in addition to yellow flame tips (this is with a pot of water on the stove, with the stove resting on a block of wood). I realize that these stoves operate under much less fount pressure than a pump-pressurized Coleman, but there doesn't seem to be much pressure when I unscrew the fuel cap. I'm a novice when it comes to these stoves, but my gut tells me that I have a leak somewhere. As I'm writing this I thought that I should do a dunk test in the sink to look for leaks, however, what do you guys think?
    Also, I read the tutorial on the dis-assembly of these stoves. What size Allen, or hex wrench do I need to remove the pip assembly from the fuel cap?
     
    Last edited: Jan 10, 2017
  2. itchy United States

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    You should find lots of advice here for the 123, and a lot of us use Coleman stuff as well.

    For being so small, these are really loud stoves and some pulsing is normal. I would say it sounds more like a loud flutter (maybe just old ears) when it is running well. And more of a roar when the pressure has built up. I would swear that some of my stoves pulse more sometimes than others, and I wonder if it may have something to do with how much fuel I started with.

    A small leak of pressure will prevent that Svea from reaching full power -- Do you think that is the case? If, shortly after turning the stove off, you notice a little pressure when opening the cap, I would guess you probably do not have a leak. A warm water dunk test is still worth a try. Another easy thing you can do this time of year is to set the stove outside for an hour or so, bring it in and vent the cap then tighten it down. After the stove and fuel warms up, open the valve and you should get a good bit of gas if everthing is tight.
     
  3. Jim Brizzolara United States

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    This week-end I'll try that -a warm water dunk test and setting the stove outside for a while. Maybe I'm being too picky; it was 12 degrees that night.
     
  4. Tony Press

    Tony Press Australia Subscriber

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    @Jim Brizzolara

    1. It's good practice to release the pressure in these self-pressurising stoves before relighting - this allows them to re-pressurise properly. But that may not be your problem.

    2. The dunk test is a good idea. When it's cold, with all outlets tight, dunk it in warm water. Do this before going to the labour of refurbishing the SRV on the filler cap, because if it's not leaking, you can use the stove.

    3. What you need to take the SRV apart depends on the shape of the fitting. The Fettle Box has the correct tool for these if you need it.

    5. A flutter is the right sound, building to a loudish roar under use. If it sound hysterical, take the pot off!

    Have fun with the 123.

    Cheers

    Tony
     
  5. Robert Bruce

    Robert Bruce Australia Subscriber

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    Pulsing is normal, there not called "choofers " for nothing. I have 123r and it pulses but they work so well.

    Cheers
    Rob
     
  6. Ed Winskill

    Ed Winskill United States Subscriber

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    If it's a flutter, rather than a lower-frequency true pulsing, then it's part of the charm of the stove!
     
  7. geeves

    geeves New Zealand Subscriber

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    the chuf is what makes the 123 so special.
     
  8. hikerduane

    hikerduane United States Subscriber

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    I was given a 123R a few years ago. Went through it, still ran off a little I thought. Ran much better when run awhile. Has yours been stored a bit?
    Duane
     
  9. geeves

    geeves New Zealand Subscriber

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    no one knows why the 123 and 123r does this. There is no real difference in the burner between this and the 8r or 71 type stoves but they dont pulse. It could be the higher surface area on the fuel in the font but that would make it better not worse.
     
  10. Robert Bruce

    Robert Bruce Australia Subscriber

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    It's a nice sound sort of reassuring, the quaint 123 and 123r are unique and a great back packing stove. They look terrific to.

    Cheers
    Rob
     
  11. Ray123

    Ray123 United States Subscriber

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    Welcome to CCS Jim.

    There's pulsing and then there's the chuffing, helicopter normal sound. I don't know which you are experiencing. One of my 123's has a pulsing startup. I believe my wick could be a little bit carboned but haven't pulled things apart to check. I put a pot on it and it immediately clears the pulsing and the stove runs strong.
     
  12. snwcmpr United States

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    Can you specify the time of the pulse?
     
  13. Jim Brizzolara United States

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    snwcmpr, when you say "time of the pulse", I'm guessing you mean the frequency? I would guess that it pulses three times a second; sorta like the exhaust of an engine at fast idle. It seems like what you guys are telling me is that these stoves pulse even when in good fettle and warmed up.
     
  14. Ray123

    Ray123 United States Subscriber

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    Does the pulse choke the flame almost like the stove has a cough? That's what one of mine does and it's not right but after I put a pot on it'll clear up. I need to address the problem but haven't gotten to it yet.

    There are many You Tube videos showing properly running 123's.
     
  15. Jim Brizzolara United States

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    No, the pulse isn't nearly that bad. The flame height doesn't change much. I will go check out some Youtube clips, that's a good idea.
     
  16. geeves

    geeves New Zealand Subscriber

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    Both of mine pulse but I have seen 1 video of one that didnt. They are worse cold a bit like a steeam train that didnt get a full head up before leaving.
    Start with a 5 second wheeze getting into a 1 second chuff fully running helecopter doing 300 mph
     
  17. snwcmpr United States

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    I have always thought that the pulse was related to the wick. That the first thing I would look at.
     
  18. itchy United States

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    I like the pulsing sound. I think 2 to 4 Hertz is about right.

    I seem to remember several discussions on the physics behind the pressure fluctuation that result in the pulse and it is nothing simple, although the wicking rate will be a factor. I am also of the impression that there is probably always a pulse but when the frequency is high enough we can no long perceive it.
     
  19. ArchMc

    ArchMc United States Subscriber

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    I think the normal pulse is more like 10 Hz, but I haven't measured it. Just estimating time as "...one, one thousand,..."

    I like that sound too; find it very comforting.

    ....Arch
     
  20. geeves

    geeves New Zealand Subscriber

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    The one I saw not pulsing I did offer to fix for the owner but they declined. It still put out much the same power just didnt sound right
     

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