Airhead rear main seal install: oil or no oil?

Discussion in 'Airheads' started by spartanman, Jun 14, 2010.

  1. spartanman

    spartanman regret minimizer

    Joined:
    Oct 17, 2009
    Oddometer:
    1,737
    Location:
    Land of High Hopes & Low Taxes
    As I understand it, Part No. 11 11 1 261 739 is an upgraded rear main seal design. It looks remarkably different than the original spring-actuated lip seal. I've read it has a teflon sealing surface and therefore should be installed dry. This is consistent with my experience on Cummins 12V diesel engines that use teflon main seals front and rear. I've also read that the BMW seal should first be soaked in hot oil before installation. What's been your experience? Thanks.
    #1
  2. wirewrkr

    wirewrkr the thread-killer

    Joined:
    May 23, 2008
    Oddometer:
    4,293
    Location:
    HIGH desert
    I've installed that teflon seal 10 times in as many years. I've never had one leak. I put mine in dry and dry. no soaking, no wetting.
    #2
  3. Hawk Medicine

    Hawk Medicine Coyote's Brother

    Joined:
    Jun 8, 2008
    Oddometer:
    3,307
    Location:
    NOR CAL
    Dry.
    #3
  4. Infracaninophile

    Infracaninophile Finding My Way..

    Joined:
    Sep 27, 2001
    Oddometer:
    7,535
    Location:
    Rhode Island, USA
    Matt Parkhouse did mine for me for while I watched (in my basement). He massaged it a bit (not sure why) and stuck it in there. Dry.

    T.
    #4
  5. bmwrench

    bmwrench Long timer

    Joined:
    Nov 10, 2006
    Oddometer:
    4,757
    The "massaging" is to shape the lip. This prevents the lip from tearing as the flywheel goes on.
    #5
  6. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,381
    Location:
    Redwood City, CA
    Easiest way is to install the seal on the "guide ring" for a couple hours. That lets the seal naturally conform to the shape when you install everything.

    Also make REAL sure the seal goes in dry and straight (use a round disc with holes for the flywheel bolts) as a pusher. If you see some shavings on the side of the disk when you finish pushing it in flush, you increase the likely hood of a later leak.
    #6
  7. spartanman

    spartanman regret minimizer

    Joined:
    Oct 17, 2009
    Oddometer:
    1,737
    Location:
    Land of High Hopes & Low Taxes
    Dry it is. Thanks all for the help. Much appreciated. Beemerguru: I borrowed an installation tool like the one you describe. Seal went in clean and straight.
    #7
  8. jtwind

    jtwind Wisconsin Airhead

    Joined:
    Nov 19, 2004
    Oddometer:
    3,485
    Location:
    Madison WI
    Mostly good advice. The new seals are something like the 4th generation and do not need oil or forming. Put them in dry, square and to the right depth and you are in business.
    #8
  9. Beater

    Beater The Bavarian Butcher

    Joined:
    Sep 3, 2009
    Oddometer:
    3,701
    Location:
    Atlanta, GA, USA
    I did it dry. No leaks, no errors, and I have about 2K miles since the service.
    #9
  10. AliBaba

    AliBaba Been here awhile

    Joined:
    May 30, 2005
    Oddometer:
    381
    Location:
    Norway
    Hmm, isn't 11 11 1 338 342 the new one?
    #10
  11. wirewrkr

    wirewrkr the thread-killer

    Joined:
    May 23, 2008
    Oddometer:
    4,293
    Location:
    HIGH desert
    Yes, this is the current part number.
    When BMW changes part numbers (which happens a lot) it doesn't always mean the part itself has changed.
    this the tool that I have been using. a pieces of nylon that I spun up in the lathe. That and a hammer and it's a snapperoo!

    Robert
    #11
  12. coastranger

    coastranger Been here awhile

    Joined:
    Jun 16, 2009
    Oddometer:
    429
    Location:
    coast range oregon
    so what happens if it goes in wet
    #12
  13. wirewrkr

    wirewrkr the thread-killer

    Joined:
    May 23, 2008
    Oddometer:
    4,293
    Location:
    HIGH desert
    Some say that is how they do it and it works fine.
    I don't care to tempt fate when it comes down to having to do a job twice.
    Whatever you want to do, do it.
    #13
  14. jtwind

    jtwind Wisconsin Airhead

    Joined:
    Nov 19, 2004
    Oddometer:
    3,485
    Location:
    Madison WI
    It wouldn't hurt if if you smear alittle oil on the edges of the seal. It's going to see oil sooner or later.
    #14
  15. RecycledRS

    RecycledRS Along for the ride

    Joined:
    Nov 2, 2008
    Oddometer:
    1,050
    Location:
    Vancouver Island
    Not knowing any better at the time I put mine in wet. Seal is working fine with 2500 miles so far.
    #15
  16. Country Doc

    Country Doc Wanderer

    Joined:
    Dec 15, 2006
    Oddometer:
    2,796
    Location:
    somwhere north of Kingston, Ontario
    I always oiled mine until I saw on the airheads list that the new seals did not require oiling.

    Anyway, I've done half a dozen and none of them have leaked, the first GS I did now has 50k miles on that main seal and still completely dry.

    I'm sure either way works fine but it appears the oil is not required.

    dc
    #16