Optimus 48 - in our garage for 30+ years... =)

Discussion in 'Optimus No:48' started by wulf, Jun 24, 2019.

  1. Doc Mark

    Doc Mark SotM Winner Subscriber

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    @wulf ,

    Greetings, and welcome to CCS!!

    The Optimus 48 is a top favorite of Sweet Bride and me! We have several of them, a few dating back to the older days, and all are excellent stoves. They are easy to fettle (repair), and very reliable. I think it SB had to choose just one cook stove, the 48 would be amongst her finalists!!

    Check with The Fettle Box, here at CCS, to buy gaskets, and a new pump leather. You should probably replace them all, just as a matter of course. It's not expensive, and doing that will garner you many more years of reliable and enjoyable use!! Congrats, and enjoy your "new" old Optimus 48!! Take care, and God Bless!

    Every Good Wish,
    Doc
     
  2. wulf United States

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    Very many thanks for the info and pointers, Doc! I will certainly do as you suggest.
     
  3. wulf United States

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    Removed the brass pump rod carefully and found the leather washer thing appears to have disintegrated. Looks like the periphery of it might actually have got stuck to the pump and then it tore away. New leather washer certainly needed lube.

    20190701_191441.jpg

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    Not sure whether that knurled knob at the user end of the pump rod comes off. If it does it might be the way to get a new washer on.

    Then at the bottom of that pump tube is what I imagine is the non-return valve. Heaven alone knows how you get that out if you have to...!
     
  4. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi @wulf. It should be relatively easy to remove the remains of the leather pump washer from the tube using a length of wire with a bend on the end to form a hook...happy fishing.

    This post describes how most air pumps work:

    Typical pump assembly

    It should be possible to unscrew the piston retaining nut, or the pump cap and knob, by gripping the shaft in leather clad jaws of a vice, and using a good quality spanner/wrench on the nut, or leather lined pliers on the knob.

    Good luck.

    Best Regards,
    Kerophile.
     
    Last edited: Jul 2, 2019
  5. wulf United States

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    Hi Kerophile,

    Great, thank you for this info. I will try to get the knob off as it looks like the shaft near the final nut might have been slightly crimped in some way to stop the nut undoing.

    Thanks again.
     
  6. wulf United States

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    Interestingly there appears to be no spring anywhere along the pumping rod...
     
  7. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    “Going in from the top” from the earlier link:

     
  8. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi @wulf. Springs on pump shafts were not installed by the majority of manufacturers of classic pressure stoves. They were an optional extra which some people believe helps the pump action.
    Best Regards,
    Kerophile.
     
  9. wulf United States

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    Very interesting! Thanks again Kerophile - valuable info. =)
     
  10. Duck United States

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    I’d research how to remove the nrv at the bottom of the pump tube before attempting it or you’ll end up like me very carefully drilling it by hand and using an ez-out. not the recommended way to do it.
     
  11. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Last edited: Jul 4, 2019
  12. wulf United States

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    Hi @kerophile,

    You're a great source of information, very many thanks.

    I managed to extract the remnants of the leather pump washer with a home-made wooden hook. I shall now try and make tools to extract the non-return valve and also to help refit the new leather washer. Then I need to get the bits to fit.

    Thanks for all your help.

    20190705_125721.jpg
     
  13. wulf United States

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    The knob on the end of the pump rod does indeed unscrew.

    20190705_133310.jpg
     
  14. wulf United States

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    There appears to be a slow leak of some sort in the area below the pre-heater pan, not easy to spot but the metal gets damp if left for a while. Assuming this is a washer leaking. You can sort-of see the leaking fuel on the lower hex in the photo.

    Any cautions regarding disassembling this bit of the stove? It's tempting to just pile in and start undoing things...

    20190705_131519.jpg
     
  15. Duck United States

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    You may just get away with tightening it. but yeah you probably should replace those two gaskets. Nothing to worry there it's pretty straight up wrench on top .wrench on bottom,turn counter clockwise(anti clockwise for our friends on the far side of the pond) remove and replace seals and put back together. Easy as pie.
     
  16. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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  17. wulf United States

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    More disassembly revealed:

    * A knackered red 'rubber' washer under the burner assembly (approx. 18 mm OD x 14.6 mm ID; 0.709 in. OD x 0.575 in. ID)
    * A knackered red 'rubber' washer under the lighter cup (approx. 19 mm OD x 14 mm ID; 0.748 in. OD x 0.551 in. ID)
    * What might be a lead sealing washer at the coupling between the base/fuel tank and the brass pillar. There's definitely something non-brass there, seems to be a metal rather than a hardened rubber.

    The red rubber washers I will try and replace with high temperature Viton washers.

    Pictures to follow.

    20190706_160924.jpg

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    20190706_160624.jpg

    20190706_160624.jpg

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  18. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi @wulf

    The washers in the burner should be heat and pressure resistant. Originally they would have been asbestos-bearing but modern versions are available which do not use asbestos. DO NOT USE VITON.

    The washer between the tank and riser is lead. If it is undamaged just leave it alone. Your stove is a collapsible model which can be partly dismantled for transport. The lead allows many cycles of assembly/disassembly unlike a fibre washer in the same position. Do not overtighten on assembly as it is possible to extrude the lead out of the joint.

    Fettlebox should soon be open and can supply the heat-resistant washers that you need:

    https://fettlebox.co.uk

    I already provided a link on how to fit the washers:

    Heat-resistant burner washers, and fitting them.

    Best Regards,
    Kerophile.
     
  19. shagratork

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

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    Excellent instructions from kerophile.