Cylinder-to-block leaking oilage...

Discussion in 'Old's Cool' started by Rapid Dog, Jan 8, 2011.

  1. Rapid Dog

    Rapid Dog bikes, booze, broads...

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    Cylinder-to-block leaking...:ddog
    1981 R100RS

    What are the odds? I was sooo careful too.Made sure everything was spotless clean, did not use hylomar between the cyl and block per advise, new cyl seal.

    Started her up and oil is bleeding out of the right side at the rear.
    I mean like a stuck pig.
    Left side is fine.

    I guess I must have F'd up the new o ring. I did use the slightest bit of lube so that it would slip into the block without getting pinched...

    What'r the chances...?

    Good nudes is it started right up!
    #1
  2. supershaft

    supershaft because I can

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    Who advises not to use sealant there??

    I spread a VERY thin layer of Durko with a #11 Exacto blade on the cyl. base.

    The trick is to retain the stud o-rings with a bit of sealant so that they do not fall out of their recesses while installing the cylinder. I double check right before the cyl gets snugged down all the way in order to make sure they are still where they should be. I have seen many a F'ed up cylinder from those o-rings getting pinched. It compromises the sealing surface big time!
    #2
  3. Rapid Dog

    Rapid Dog bikes, booze, broads...

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    ...you called it SS. Right side is fine and I used no sealant.
    Right side pukking was a pinch o-ring...

    Better building in the future...:D
    #3
  4. supershaft

    supershaft because I can

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    I hope your cyl and case are OK. Look real close. That pinched rubber very often makes the aluminum give and then you have an uneven sealing surface. Theoretically the oil won't get past the o-ring but I don't think that theory works very well outside of the drawing room.
    #4
  5. Rapid Dog

    Rapid Dog bikes, booze, broads...

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    ....no, it was definitely pinch, like in half...a real screw-up.
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  6. supershaft

    supershaft because I can

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    I don't think you are following me RD. I am trying to warn that the pinched rubber o-ring will make the cylinder's and case's metal give way and ruin the flat sealing surface. Does that read right?
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  7. fishkens

    fishkens Long timer

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    SS, I get it. If the o ring wasn't in the groove it could deform the alu seating surfaces when the head bolts were torqued.

    Here's hoping that didn't happen in this case.

    FWIW, I've used Hylomar at the cylinder/case interface w/o problem.

    If the OP's bike is leaking like a "stuck pig" something's definitely wrong.

    Hopefully a correct reassembly will resolve the problem.

    And I'd suggest using Hylomar unless I've missed the latest memo (which very well may be the case :D).
    #7
  8. Renner

    Renner rockin' the toaster

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    I believe RD has already succeeded the second time around.
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  9. Rapid Dog

    Rapid Dog bikes, booze, broads...

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    ...I checked the mating surfaces, all good. I'm putting it back together this morning. I'll keep ya posted.
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  10. supershaft

    supershaft because I can

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    Great. I really don't know if it makes any difference or not but I believe that the damaged surfaces that I have seen from pinched o-rings had been run with the o-ring pinched for some time. Good luck Rapid Dog!
    #10
  11. Country Doc

    Country Doc Wanderer

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    FWIW, I battled with slightly weeping cylinders on my slash-5 for most of the year. Tried Hylomar, grey Permatex, Threebond, blah blah.

    The only thing that worked well was Loctite 518. It's a case sealant for flush-mated aluminum surfaces. I believe it's an anaerobic cure and will not clump out in your oil like silicone-based sealants.

    I know your bike is different RD, and may not require any sealant at the base due to the O-ring, but this is just another data point for someone looking for a decent cylinder base sealant.

    dc
    #11
  12. fishkens

    fishkens Long timer

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    Have you had the jugs off since? Did they come off easily? Any nasty residue?
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  13. outfit

    outfit Been here awhile

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    Good oil pressure though:thumb
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  14. Country Doc

    Country Doc Wanderer

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    I haven't had the jugs off, but I've had VW aircooled motors apart a few times using the same sealant, and it's easy to clean up. Brake cleaner and a shop rag.

    A damn sight easier than the Permatex grey, which took FOREVER to painstakingly clean away.

    The #518 is good stuff. Pricey for a small tube, but seems to work great. :thumb

    dc
    #14
  15. Rapid Dog

    Rapid Dog bikes, booze, broads...

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    Well, a notch in supershafts knowledge belt...after pulling the cylider, I could feel a slight indentation on the block below and down from the rear o-ring. I wa spanicked for a moment. Weather my sanfu did it or someone previous, it was there.
    Took my chances and threw the dice, got a fresh tube of Hylomar and brushed it lightly on both srrfaces and locked it down.
    Hapy to say I took the bike out for a shakedown and no, but none, leakages.
    Phew! Feel like I dodge a major bullet! :freaky
    Bike runs great I must say, no smoke, no leaking, no popping or otherwise.
    I'm a happy boy!
    [​IMG]
    #15
  16. supershaft

    supershaft because I can

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    A notch in my belt?!? Not in mine! I am just glad I could help.
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  17. Rapid Dog

    Rapid Dog bikes, booze, broads...

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    [​IMG]
    #17