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Thread: Hole in engine case

  1. #1

    Hole in engine case

    I inherited a 2015 F800 GS with a small hole drilled in the engine case, at the heat exchange tube fitting. The guilty party was trying to extract a bolt after they broke the head off. Now when you're all done laughing and shaking your heads I'd like to pick some brains...Has anyone ever dealt with an issue like this? Is there a possibility of an expert machine/weld shop filling the hole and retapping for said broke bolt? The bike has 25K miles on it and other than needing new tires is in otherwise excellent condition. Just thought I'd ask before investing a lot of time online and on the phone researching this.

  2. #2
    #13338 PGlaves's Avatar
    Join Date
    Oct 2003
    "Big Bend" TX
    I an not sure where on the engine this hole is, nor how big it is. That said I would be fairly sure that a good machine shop can fix this. One approach would be to over size the hole and use a threaded insert. If that is not possible due to interference from something too close to the hole then the suggestion that it could be welded and then drilled and tapped would be likely to work. A few photos would help us understand.
    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

  3. #3
    Registered User
    Join Date
    Aug 2018
    Fargo, ND
    A little more info on the hole would help. If is is not in hot exhaust I would clean the hole well, and use JB Weld over the hole and keep and eye on it.

    Did the previous owner drill through the broken bolt and continue through the crankcase?

    what size threaded hole?

    Another choice would be to drill and taper it to a standard size and Locktite a set screw into the hole.
    From the only real Fargo, ND!

  4. #4
    Cum opus clava fecit nihi
    Join Date
    Mar 2003
    Okanagan Valley, BC
    Are you referring to one of the M6 bolts that holds the fitting at the end of the tubes to the engine case?

  5. #5
    This is the best picture I can get. I exaggerated the extent of the damage based on the confession of the guilty party. After getting down on the creeper for a closer look, I determined the case was not penetrated and the issue will be removing the remaining portion of bolt, over drilling and installing an insert. As always I appreciate input from those know how to 'fix things'. Now I just need to find a place to store another motorcycle.

  6. #6
    Back in the Saddle mcmxcivrs's Avatar
    Join Date
    Apr 2003
    I would think that even if that had penetrated the case. Once the remaining bolt material is removed, a plug with a blind hole could be fashioned and sealed into the hole in the case. If the case is not drilled through, then a typical thread repair method should fix it up.
    Ed Miller, Calgary, AB
    2008 K1200GT, 2019 F850GSA

  7. #7
    I would agree Ed and I believe I have found a guy with the expertise to do it. I'll follow up when the fix is done.

  8. #8


    Mustering ALL of the patience and finesse I have, I was able to remove the broken bolt with a Dremel tool and several different bits. I then used a Time-sert kit to install a threaded insert. As the old saying goes "I'd rather be lucky than good". The insert was perfectly centered on the coolant tube flange bolt hole. After several warming up and cooling down cycles followed by one highway run, it's leak free. And I am very relieved! The one take away from this repair, should I have to replace another broken bolt in this manner, is to be careful with how much material is removed from the outside wall of the original bolt hole. The wall of the insert is not very thick and the over drill is not significant.
    Attached Images Attached Images

  9. #9
    Fortis Fortuna Adiuvat Omega Man's Avatar
    Join Date
    Jan 2010
    Thanks for letting us know how you made out.
    "You can do good or you can do well. Sooner or later they make you choose." MI5
    Mod Squad
    2009 F800GS 1994 TW200

  10. #10
    Back in the saddle again mikegalbicka's Avatar
    Join Date
    Aug 2014
    Good job!

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