Problem with Optimus 8

Discussion in 'Stove Forum' started by Yannick Michel, Sep 8, 2021.

  1. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi @Yannick Michel when you receive your graphite tape you will see that this tape has little flexibility nor mechanical strength in tension.

    Tape is a just a useful form to allow you to position the tape where it is needed. Once there it is enclosed and you make use of its lubrication properties and compressive strength.

    PTFE in contrast has considerable flexibility and directional tensile and compressive strength, as well as chemical and temperature resistance. It is specially formulated for thread filling and sealing under adverse conditions.

    Best Regards,
    Kerophile.
     
  2. OMC

    OMC United States Subscriber

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    Welcome Yannick,
    Very nice stove. The initial problem was leak at packing nut.
    Re: He "... can’t see a graphite packing" Once compressed graphite surface can be smooth with a metallic appearance. We will want to confirm the graphite was removed?

    I'm prompted to post, if/when graphite is completely removed...
    Re installing graphite, "a washer" was twice mentioned above.
    As I understand it,
    for the 8 (and many early models) there is no washer (proper placement of washer should not come up).

    If new graphite is needed, the assembly is as per instructions that kerophile:thumbup: linked to in his 1st reply to this thread (no washer there fwiw).

    Re the washer: Catalogs indicate Optimus 1st integrated that washer in '73 w/ "new" 123R.
    At that time or soon after the washer was also integrated into the 8R.
    FYI catalogs do not show the washer on 8s pre-1957 nor on 8Rs c1957 thru 72.

    My impression, out on a bit of a limb here, "that washer" is not present on any pre-1973 Optimus / Primus / Svea / Radius sm. petrol stoves.
    Now, that ^^^ may be proven not entirely accurate but that is my impression to-date.
    Good luck Yannick.
     
    Last edited: Sep 8, 2021
  3. Yannick Michel France

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    Thanks again Kerophile and thanks OMC.

    I appreciate your help and will come back as soin as I receive the graphite foil.

    I found at home a kind of graphite paste to lubricate and which supports temperatures to 300 degres Celsius. Would it be a good product by chance to seal correctly these 2 parts (tank and burner tube)??
     
  4. Yannick Michel France

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    And to answer to OMC here are the 2 parts I found on my Optimus 8. I see no graphite.

    so when I receive the graphite tape, where exactly should I fix the tape on the spindle ?? In the part circled in red I suppose ?
     

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    Last edited: Sep 8, 2021
  5. hikerduane

    hikerduane Subscriber

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    I use the graphite paste on some pieces, keep excess away from end to avoid clogging.
    The tape goes just before the packing nut as the nut is one end that compresses the graphite. You may have to use some force to start the nut if too much tape is used. Tighten to the point that the spindle starts to get stiff to turn.
    Duane
     
  6. OMC

    OMC United States Subscriber

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    Mine, assembled, there are threads visible. 3 mm gap as the packing nut is bottomed against the graphite. If graphite is missing it seems
    yours
    might screw in further (& have no threads visible)?
    IMG_7471.JPG

    and here too ... are the 2 parts I found on my Optimus 8,
    graphite is not on the spindle
    IMG_7473.JPG
    in
    digital image w/flash.. why that does look like graphite down inside the valve.

    "Just looking at it" down inside looks like it could be flat metallic surface.
    Is that graphite down in there, or not (just looking at it), for me is not obvious.
    and is why i said above "We will want to confirm the graphite was removed?"
     
    Last edited: Sep 8, 2021
  7. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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  8. Yannick Michel France

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    @OMC here is mine assembled. I have a gap of… 5 mm !
    And your idea that the graphite is in the valve is may be correct.
    Please see photo of the inside of the tube.
     

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  9. OMC

    OMC United States Subscriber

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    yep.

    I do not presume you need to remove your graphite?
    .. is that "the fix" or best route, I do not know.
    I do have to head to an appointment, so that's all from me.

    I defer to others for what next.

    ie Duane "I use the graphite paste on some pieces..." maybe?
     
  10. Yannick Michel France

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    @kerophile i think the part 389b is inside the tube (see photo in my previous message).
     
  11. Yannick Michel France

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    @hikerduane Thank you.
    Do you think a paste supporting 300 degres celsius is enough for sealing the tank/tube ?
     
  12. hikerduane

    hikerduane Subscriber

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    That joint won't get that hot so close to the tank and some fuel flow. I don't use the graphite paste much, discolors the fingers and dries out, not sure it makes a good seal. I use teflon paste most of the time, stands up to heat unless in close proximity.
    Duane
     
  13. shueilung.2008

    shueilung.2008 Subscriber

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    @Yannick Michel

    I've used teflon tape to seal the treads in my Optimus #8 aluminium cased (the same as yours) back in May 1917. Since then, I use it twice a day (minimun) to make me coffee. She`s working perfectly for more than four years now.

    Foto0555b.jpg

    Foto-0005.jpg


    As for the graphite packing, you must try to adjust the stuffing box (nut 388b) when the stove is warm or "in use". It worked for me that way.

    Congratulations, you have one of the most dependable mini-stoves I have! (don't let my others Primus #71's hear that... :mrgreen:)

    Enrique

    PS: By the way, I can see marks of a wrench in your images of the riser, you better use the @presscall metod:

    Foto0553.jpg
     
    Last edited: Sep 9, 2021
  14. shueilung.2008

    shueilung.2008 Subscriber

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    @Yannick Michel

    BTW, these are the correct spare parts for the Optimus 8F from a catalog from 1956 (in swedish)

    Optimus_1600_41.jpg Optimus_1600_42.jpg

    And in english:

    1222779168-55.jpg

    Take care.

    Enrique
     
  15. Yannick Michel France

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    @shueilung.2008
    Sorry for my late answer Enrique. Thank you for your messages. I live this stove enen if it seems not to be as powerfull as the Svea 123.

    i received the graphite foil and was able to fix the problem.
    I still have a little flame (after arounf 15 minutes of burning) betwwen the tank and the tube.
     
  16. shueilung.2008

    shueilung.2008 Subscriber

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    @Yannick Michel

    Here?

    Foto0558b.jpg

    Have you employed the teflon tape?

    Take care, that is no good. Too near to the fuel!!!!!

    Enrique
     
  17. Yannick Michel France

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    @shueilung.2008

    Yes it is here. Teflon tape or teflon paste ? Did you have this problem on yours ?

    Yannick
     
  18. shueilung.2008

    shueilung.2008 Subscriber

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    @Yannick Michel

    No, usually when I dissasemble a Primus 71, Optimus 8 or 8R, I put teflon tape or graphite grease in the treads to easy the dissasembly in some future. So the treading do not get stuck.

    Another cause may be the overtightenig in the assembling can have caused a crack in the tank treads. That may be resolved with tank-sealer that stands high temperature, but it will be difficult to dissasemble again later...

    Get an magnifying glass and search for this kind of damages. This can be the cause of the low power of the flame too, as the Optimus 8 is as powerful as the Svea 123 when in good condition.

    My best wishes in task Yannick!

    Enrique
     
  19. Yun124

    Yun124 Subscriber

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    Hello, for my cases I've been usually using Permatex or Loctite LB8008 copper based anti-seize paste. Hope my application is not wrong...
     
  20. Yannick Michel France

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