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Thread: '85 K100RS stripped crankcase cover bolt

  1. #1
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    '85 K100RS stripped crankcase cover bolt

    need some help?? lm down here in Monahans, West Texas and lm new to BMWMOA,l discovered l was leaking oil on the right side, farthest bolt front, right behind the radiator hose,,,,,the crankcase cover bolt is stripped as is the fitting,,,,,,,,,,,,,,,this happened as a result of a restore job and the bolt was overlooked,probably cross threaded,,,,,where could l get the most local service possible and any suggestion to keep me road worthy temporarily? thanx a million in advance!!

  2. #2
    Benchwrenching PGlaves's Avatar
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    It takes an M6x1.25 metric helicoil. Any good auto parts store can get you the kit with the tap, coils, and insertion tool.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

  3. #3
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    Welcome to the forum!

    It probably wasn't cross threaded. It was probably over torqued.

    The correct torque for those bolts is only 6 1/2 ft/lb. A normal 1/2" drive torque wrench will not work at that low of a torque. You need an inch/lb torque wrench set to 78 inch/lb. Most people do not have one and tend to over tighten these bolts.

    The bolts have a shoulder on them that is designed to bottom out at the correct torque. There are rubber bushings on the bolts that push against the valve and crank covers to apply the correct pressure to the gaskets. When the bushings get old and hard, they don't apply adequate pressure to the gaskets and you get a bit of seepage. The first thing the uninformed wrench would do is tighten down on the bolts. Steel bolts bottomed out on an aluminum head or block don't take much of a turn to pull the threads out of the head or block.

    Any time anyone is thinking of pulling the valve cover or crank cover for the first time, you should have a set of new bushings (if I remember right, they're around $.79 ea.) ready to replace the existing ones if they turn out to be hardened. If you've already replaced them, they should be good for many years before they lose their resiliency.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  4. #4
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    so what is my option??
    Last edited by 98lee; 12-28-2012 at 04:37 PM. Reason: My appologies Preacherboy. I accidently deleted part of your post. Trying to do things on an iPad combined with the power of moderator access can lead to some unintended consequences.

  5. #5
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    Quote Originally Posted by PGlaves View Post
    It takes an M6x1.25 metric helicoil. Any good auto parts store can get you the kit with the tap, coils, and insertion tool.
    Thank you Paul!! can you recommend anyone in my area to machine this job for me?? l don't wanna risk doing it

  6. #6
    A bozo on the bus deilenberger's Avatar
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    Dear Preacherboy (real name? We're friendly around here..)

    Please read: http://www.bmwmoa.org/forum/showthre...r-thread-title!

    In this case I can't add it since I can't find it in any of your postings. This may be useful info, or may help draw someone into the thread that can help you out.

    Thanks for your cooperation!
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  7. #7
    Rally Rat
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    Quote Originally Posted by pglaves View Post
    it takes an m6x1.25 metric helicoil. Any good auto parts store can get you the kit with the tap, coils, and insertion tool.
    6 x 1.0

  8. #8
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    1985 Beemer K-100 RS

    Quote Originally Posted by deilenberger View Post
    Dear Preacherboy (real name? We're friendly around here..)

    Please read: http://www.bmwmoa.org/forum/showthre...r-thread-title!

    In this case I can't add it since I can't find it in any of your postings. This may be useful info, or may help draw someone into the thread that can help you out.

    Thanks for your cooperation!
    My name is Jack Antosy,l ride an old 1985 BMW K-100,what use to be an RS l guess?? lm new as you know and l would like to get hooked up with some local folk here in West Texas. lve had the bike bout 10 years and recently had done a restore job on it, lm also new to West Texas and service is well?? non-existent

  9. #9
    A bozo on the bus deilenberger's Avatar
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    Hi Jack,

    Welcome to the forums. Hopefully someone near you may spot the thread and have the Helicoil kit.. It's not an unknown thing to happen. And as was suggested - probably a good idea to replace all the rubber donuts while the cover is off.

    FWIW - when I owned an early K - I'd tighten those bolts with a 6" long box wrench, using just two fingers for the final tightening. Once you feel the shoulder "seat" against the head casting, stop. Going further will do nothing useful, and may well cause the threads to strip out as you experienced. It's one of those "has a feel to it" sort of things.

    Best regards!
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  10. #10
    3 Red Bricks
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    Quote Originally Posted by Preacherboy View Post
    so what is my option??



    Your option, as Paul stated is to have a Heli-Coil installed. BUT, Lostboy is correct. The correct size is 6mm x 1.0.


    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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