Cracked threads in the head, please tell me it's not as bad as it looks.

Discussion in 'GS Boxers' started by Stre7ch, Oct 28, 2014.

  1. Stre7ch

    Stre7ch Been here awhile

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    So there I was, doing an oil change, checking valves etc... And I go to put the left valve cover back on. Suddenly the bolt gave way. I took the cover back off to check and this is what I found:

    :eek1

    What the hell do I do now? I put the cover back on with minimal torque on that bolt, then took it for a short ride, it doesn't seem to be leaking... But is it going to be ok? Should I leave it, maybe go to my buddies machine shop and see what we can do? Please don't say I need to get a new head.

    Attached Files:

    #1
  2. Britome

    Britome Get Free

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    Don't freak. Very common. A helo coil is your best bet.
    #2
  3. ragtoplvr

    ragtoplvr Long timer

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    relax,this is quite common.

    It can be fixed. You will not need a new head.

    I would use lots of spray cleaner, I use carb, then a little brake cleaner to degrease the area.

    I would mix some JB weld, devcon titianum epoxy or the like and force it in the cracks, then gently force the cracks together, and let cure. Then I would add a layer of the same epoxy around the hole and let cure. Then I would add a helicoil.

    This is a shoulder bolt, once the shoulder bottoms, quit tightening it.

    Rod
    #3
  4. JerryH

    JerryH Proudly Powered By Internal Combustion Supporter

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    Actually, you DO need a new head, unless a professional can fix it by welding. A makeshift repair as suggested MAY hold for awhile, but vibration will cause the cast aluminum to crack even more over time.
    #4
  5. pistole

    pistole Long timer

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    I wouldn't use any adhesive there. Its exposed to both heat and oil.

    and a helicoil isn't going to help since the bolt seat is cracked.

    if the cracked piece came off , it would go into the engine....

    so , perhaps ride it to a place which can weld aluminium and ask them for an opinion.
    #5
  6. Corroded

    Corroded Been here awhile

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    If the thread alone had pulled or stripped a helicoil would do, but the aluminum is cracked/split and if you helicoil it could fail. If it fails then you could end up with big chunks of aluminum in your engine.

    Do you have any idea how much torque you applied? its possible there was a flaw in the metal but either way it needs welding or replacing. Not sure if they can weld that in-situ or if you have to pull the head to get it done?

    :cry
    #6
  7. def

    def Ginger th wonder dog

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    Weld, flatten (file to the same height as before. The OHC bolt bottoms applying the pressure to the gasket to seal the surfaces), drill, tap and be careful when you snug the OHC bolts henceforth.
    #7
  8. Stre7ch

    Stre7ch Been here awhile

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    Just contacted my go to aluminum welder guy... He says it's a no go, and he doesn't know anyone who could do it... I wish it were as simple as JB weld, but I don't want to risk that coming undone. Looks like it's a new head for me. :cry

    Anybody have a link to where I can get one, or know somebody with a spare?
    #8
  9. JimVonBaden

    JimVonBaden "Cool" Aid! Supporter

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    This, and you do not need 40Nm of pressure on the bolt! It is only 8Nm, barely snug by a light tug.
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  10. JimVonBaden

    JimVonBaden "Cool" Aid! Supporter

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    I promise you it has been done before. Talk to a competent machinist.
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  11. Britome

    Britome Get Free

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    This happened to me. My son totaled his 2007 GSA and I rebuilt it with a salvage title. On the side that had the broken valve cover, one of the bolt holes was warped and cracked. It was epoxied and helo coiled. One year and 15k miles later all is still good.
    #11
  12. mouthfulloflake

    mouthfulloflake Not afraid

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    No worries really if it breaks off and falls into the sump.

    there is a strainer in there,and it is typical to find all sorts of treasures in a sump.


    if its not leaking now I wouldnt worry about it.

    next time you remove the bolt,maybe clean the hole and crack well.

    fill with some sort of epoxy or JB weld.

    put a stud in place of the bolt.

    let it cure well, then that one corner of the valve cover an just wear an acorn nut.
    #12
  13. Stre7ch

    Stre7ch Been here awhile

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    Well, my friend said it would have to be super heated, and that it'd ruin the integrity of the metal. It is cast aluminum right? Do you have any links to it being done?

    Wouldn't happen to have a picture of how the epoxy has held up, would ya?
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  14. bemiiten

    bemiiten League of Adventures

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    I'd mask the area off , clean it and reinforce with some epoy in the crack and around the broken part to try and keep the crack from spreading. Clamp it shut and let it set up. If the casting is deep enough, a long Timesert that reached down to the good material would take the stress off the broken section.
    #14
  15. JimVonBaden

    JimVonBaden "Cool" Aid! Supporter

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    No offense to your friend, but he obviously does not know how to weld this. Take it to a machinist.

    If you want to see how it is done do a search in the Garage section. This comes up often enough you should be able to find it.
    #15
  16. GrouchyGeezer

    GrouchyGeezer idjit galoot, still

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    I'm with Jim, this is not a difficult repair job. The trickiest part of this type of weld repair is to disconnect all electrical connections to the frame. You don't want to fry the bike's electrics, that would make replacing the head look like chump change.

    Edit: Sometimes electrical issues can be avoided by locating the welder ground as close to the weld as possible. But, I am not familiar with welding on a CanBus machine. Perhaps others know.
    #16
  17. ragtoplvr

    ragtoplvr Long timer

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    production car engine builders weld aluminum heads every day, day after day. In much more critical areas like between the valves and next to the spark plug. This area is thermally isolated from the hot part. Any decent welder could weld it, it only has to hold a screw that is not very tight.

    JB weld will hold for years, and can be easily renewed if/when it fails. I have a 11 HP briggs lawnmower, where the block broke somewhat like that at the carb flange. Much more heat and much more vibration. I had to renew it once in the 15 years I mowed with it.

    Rod
    #17
  18. JimVonBaden

    JimVonBaden "Cool" Aid! Supporter

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    This is an 1150, so not Canbus, but care should be taken anyhow. Isolating the battery and keeping the ground close should do it.
    #18
  19. Byrdguy

    Byrdguy Long timer

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    A good welder can fix that, no problem. Find one, pay him/her, ride with confidence that the repair won't fail.
    #19
  20. Beezer

    Beezer Long timer Supporter

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    the fix has to be adequate for the application. here's a similar one I did a while back.... grind out broken parts (or not), drill & tap for a bigger bolt.

    [​IMG]

    the bigger bolt is drilled & tapped to receive the original fastener & installed with Locktite red...

    [​IMG]


    as for removing the battery when welding... that needs some discussion. seems to me to be counter productive since the battery acts like a big capacitor & soaks up transient spikes. there are a number of connections that go to the PCM & sensors & etc that are not directly connected to the battery. I never remove the battery. I have welded on cars as well as high buck bikes like BMW and KTM no problem
    #20