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Thread: Snapped the valve cover screw off in the head...BUMMER!!!!

  1. #16
    Registered User dieselyoda's Avatar
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    What's that guy say, "UFDA happens"? I googled that.

    Quote Originally Posted by scott.lambert View Post
    Yeah, I know how they work. Supposedly.
    On they other hand I'm the only one here, so guess who stripped it?
    I should invest in a little torque wrench I guess, one that clicks so I don't need my readers on to use it.
    I'm always amazed by these posts. Holy Crap, (can I say that?) there are some smart fellers posting comments. I can say, with absolute certainty based on 35+ years as an HD Mechanic, torque wrenches, good ones, can easily be your best friend, and an enemy.

    I had a situation very recently where we were torquing a cylinder head with "torque to yield" head bolts. Followed the book, seemed odd at the time the torque was so high, but.......Snapped the first three head bolts at the final torque. Pulled the head, removed the remainders, tried again with new bolts, SNAP!

    Torque wrench calibrated in August (Certified), head bolts OEM. Service manual, one serial number out of sequence.

    Trust you gut instincts every time.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "Life isn't about how fast or how high, it's about how well you bounce."

  2. #17
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    Quote Originally Posted by dieselyoda View Post
    I'm always amazed by these posts. Holy Crap, (can I say that?) there are some smart fellers posting comments. I can say, with absolute certainty based on 35+ years as an HD Mechanic, torque wrenches, good ones, can easily be your best friend, and an enemy.

    I had a situation very recently where we were torquing a cylinder head with "torque to yield" head bolts. Followed the book, seemed odd at the time the torque was so high, but.......Snapped the first three head bolts at the final torque. Pulled the head, removed the remainders, tried again with new bolts, SNAP!

    Torque wrench calibrated in August (Certified), head bolts OEM. Service manual, one serial number out of sequence.

    Trust you gut instincts every time.
    Oh, sure, the Utah Funeral Directors Association. Everybody knows that.

    There was a time when I could probably tell you how many pounds I was putting into it.
    Not so sure anymore, the RT doesn't break down enough in a big way to get a lot of practice in.
    I've never worked with to-yield fasteners, I don't think I would try it without some kind of torque wrench.
    I don't know, can you tell you're at the yield point by feel? I guess so if you were doing it all day.

    Generally I make sure my wrench handle is short enough that the maximum torque is limited by either tool deflection or hand pain.
    I'm still befuddled how I did this. I'm thinking there weren't many threads there when I got it.

    I have a similar bolt-snapping story. Ford Taurus, making an awful racket. Took a peek under, the crank pulley was about to fall off. Three bolts were there, though loose, and one completely missing. Very difficult to find this bolt, would have to order from Ford and wait. Finally I found one at a salvage yard. Both the Ford parts guy and the salvage guy made it a point to emphasize this was a specially hardened bolt made for the high torque required to cinch it down properly. Nervous now, I found the Taurus service manual at the Library (the official Ford service manual) and sure enough the torque number was 142 ft-lbs. I had to think about that for a minute to realize that's an awful lot. But ok. Manual says to loctite them and torque them down. So here I go, red loctite and my 1/2" drive beam, I didn't get hardly anywhere before the first one snapped.
    Well maybe that was the salvage one, try another one. snap.
    I shoulda knowed.
    I managed to get the other two backed out. Now, here I am, nothing to get a grip on, red loctite hardening... It's good to have family and friends who can run-go-get extractors and such while I'm drilling a hole to put them in. Don't even have time to cuss it proper.
    After some more research, a later edition of the same manual has it as 142 INCH pounds. And now try finding two of those bolts.
    So, yeah listen especially when they're screaming STOP.

    I have decided to go with heli-coil and not the more robust looking time-serts, they look a little easier to install and a buddy has direct experience with them. And it's a low-stress application. Although, I may procrastinate a little longer - it isn't leaking yet, even after a high-speed run down to Fayetteville BB&B and back yesterday. The gasket is squished enough I guess. I'm considering doing all eight, just to replace the aluminum threads with steel. I guess by the time I get that done I'll be the expert on heli-coil.

  3. #18
    Registered User lkchris's Avatar
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    Be good to understand that this really is NOT an application for a torque wrench.

    You don't really want to torque a bottomed screw.

    The figure from BMW is mostly gratuitous, but I suppose could help those that don't get mechanics ... but would they own a torque wrench in the first place?

    I'd be surprised to learn of a pro BMW tech (BMW trained) using a torque wrench on these screws.

    Broken screws here represent "karma" to me, as it represent payback to those who would dismiss professionals and use of professional tools, thinking apparently they're overrated or some sort of conspiracy to steal your $$. They're not. Even if it's DIY, you have to pay to play. TINSTAAFL.
    Kent Christensen
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    '12 R1200RT, '02 R1100S, '84 R80G/S

  4. #19
    Left Coast Rider
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    Quote Originally Posted by lkchris View Post
    Broken screws here represent "karma" to me, as it represent payback to those who would dismiss professionals and use of professional tools, thinking apparently they're overrated or some sort of conspiracy to steal your $$.
    Nice.

  5. #20
    Benchwrenching PGlaves's Avatar
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    Not to pick nits, but technically this is not a "bottoming" capscrew which implies the threaded end reaches the bottom of its hole. It is a shouldered capscrew where the unthreaded shank is a larger OD than the thread section. The capscrew threads into the hole until the shoulder hits the surface of the head, and will go no further short of twisting off the thread section or stripping the threads. Once shouldered the capscrews in unison hold the gaskets and the rubber collars on the capscrews compressed.

    General note: if you have a leak trying to tighten these almost never helps. If it is truly loose - shoulder not contacting the head, then OK, but otherwise trying to tighten them does nothing to the gaskets or the rubber seals on the capscrews.

    The threads are M6 x 1.0
    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

  6. #21
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    Quote Originally Posted by PGlaves View Post
    The threads are M6 x 1.0
    Thanks, Paul.

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