Crank bolt puzzle?!
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This is a discussion on Crank bolt puzzle?! within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I have gathered the necessary parts to replace the timing belt and today was looking at the crank bolt. When ...

  1. #1
    He simply abides. SD_GR's Avatar
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    Crank bolt puzzle?!

    I have gathered the necessary parts to replace the timing belt and today was looking at the crank bolt. When the motor is on, the pulley looks straight, the external belts look straight, there is no "wobble" visible in either the pulley or the belts. However, the bolt head itself looks like it is spinning eccentrically, or like the head is "wobbling."

    I asked around and got a couple opinions:

    1. Cross-threaded crank pulley bolt. However it seems to me this is not easy to do since the opening for the bolt is narrow, and since to generate the amount of "wobble" I appear to be seeing would require an angle on the bolt head that would probably mean the pulley would not seat correctly. Right?
    2. Crank walk. Seems unlikely; also seems like the pulley would wobble along with the bolt. Yes?
    3. Malformed or distorted bolt head. The bolt has been removed once before, by the dealer for warranty work. This makes the most sense to me. Yes?

    The car runs fine. The belts on the outside are fine; the pulleys are fine, and there is no hint of any problem other than a bolt head that does not seem to rotate "evenly" when I look at it (it's like the bolt head is not in the middle of the bolt, if that makes sense; a "tilted" bolt would explain it but I can't figure out how the bolt would "tilt" that much and still keep everything together for so many years.

    Any opinions? I'm going to start removing stuff over the weekend but if I am going to have unpleasant surprises I'd like to have a plan B ready (I don't know how I would deal with a cross-threaded bolt -- do you?).

    Thanks!
    SD
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    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
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  3. #2
    Registered User teflon_jones's Avatar
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    If the bolt has been removed before, then I'd go for 1 or 3. I've cross-threaded bolts myself that were mega big and in a very tight spot. Sometimes it makes it easier to cross-thread because you don't think the bolt could possibly be cross-threaded. Get it in there a little bit wrong, add an impact wrench or some other big wrench, and it'll happen easily.

    Why can't you just take it out and check?

    I'm still struggling with how you'd bend the head out of place taking it out. I'm assuming the bolt is marked as an "8" or "5" which means high-strength. How do you just bend the head?
    Last edited by teflon_jones; 11-23-2010 at 04:16 PM.
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    Resident meany-rator 06wrx4me's Avatar
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    Bolts such as he crank bolt are generally "torque to yield" and as such should be a one time use bolt, same as head bolts. I'll bet you anything they impacted that bolt off and impacted it back on.

    I suggest you source another new bolt from the dealer, remove that one and **** can it.

    I'd bet its not cross threaded.
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    He simply abides. SD_GR's Avatar
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    I have already purchased a replacement bolt.

    I really do have to wonder what happened... I'm going to take it apart this weekend and I'll update on the issue. As long as I can get the old bolt off and the threads in the crank are OK, all is well. That's my only real concern -- the threads in the crank!

    OK, I'll keep my fingers crossed and let you guys know.

    Thanks!
    SD
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    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
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    Resident meany-rator 06wrx4me's Avatar
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    Quote Originally Posted by teflon_jones View Post

    I'm still struggling with how you'd bend the head out of place taking it out. I'm assuming the bolt is marked as an "8" or "5" which means high-strength. How do you just bend the head?
    Easy, stuck crank bolt (which they usually are) and a 3/4 or 1 inch impact. Or a super strong 600+ ft-lb 1/2in impact.

    When we were doing the timing belt change on my bro-in-laws lexus the bolt was in soo tight (because of electrolysis), that I was bouncing at the end of an 8' cheater bar (for 30 min or more) trying to get it loose.

    200lbs x 8 ft= 1600ft-lb moment.

    Max torque on a 5/8 fastener even grade 8 is 230ft-lbs dry (no lube).
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    Administrator Trainrex's Avatar
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    Sprios,

    Mine does the same thing. I've also seen countess other cars do the same.

  8. #7
    He simply abides. SD_GR's Avatar
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    Quote Originally Posted by 06wrx4me View Post
    Easy, stuck crank bolt (which they usually are) and a 3/4 or 1 inch impact. Or a super strong 600+ ft-lb 1/2in impact.

    When we were doing the timing belt change on my bro-in-laws lexus the bolt was in soo tight (because of electrolysis), that I was bouncing at the end of an 8' cheater bar (for 30 min or more) trying to get it loose.

    200lbs x 8 ft= 1600ft-lb moment.

    Max torque on a 5/8 fastener even grade 8 is 230ft-lbs dry (no lube).
    So you're saying they gorilla'd it off, distorting the bolt face? That's actually good news all things considered. I'm going to toss the bolt anyway and use a new one. Hopefully you're right!

    Otherwise, how do I deal with a stripped crank?! I don't think an insert would hold the torque necessary, right? Would I be looking at... gulp... removing the crank?!
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  9. #8
    He simply abides. SD_GR's Avatar
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    Quote Originally Posted by Trainrex View Post
    Sprios,

    Mine does the same thing. I've also seen countess other cars do the same.
    Trainrex, thanks! I have not seen any do that. So the bolt is likely OK -- and more importantly, the threads are likely OK?

    {Overfed hellene sits back in chair, sighs in relief...}
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  10. #9
    Administrator Trainrex's Avatar
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    Quote Originally Posted by SD_GR View Post
    So you're saying they gorilla'd it off, distorting the bolt face? That's actually good news all things considered. I'm going to toss the bolt anyway and use a new one. Hopefully you're right!

    Otherwise, how do I deal with a stripped crank?! I don't think an insert would hold the torque necessary, right? Would I be looking at... gulp... removing the crank?!
    An insert would work just fine of that were the case. There isn't that much torque needed to hold a crank pulley on.

  11. #10
    He simply abides. SD_GR's Avatar
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    That's good to know too! OK, so I'm going to go with

    Plan A: Act like nothing's wrong; replace the timing belt and other stuff, put it all back together, and use a new crank bolt from the dealer that I've already bought.

    or

    Plan B: Come back here crying about inserts and all that if and only if necessary -- and hopefully it won't be.

    Thanks guys!

    SD
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  12. #11
    Resident meany-rator 06wrx4me's Avatar
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    Cranks are usually hardened, and typically even with a bolt that is an animal to get out, the threads are ok. I have seen crank bolt threads distorted or stripped and the crank is fine. IME if the crank bolt is cross threaded or seized, the head just snaps off, but its rare.

    You'll be fine, when we did the t-belt on my buddies bugeye, the crank bolt was cake.
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    He simply abides. SD_GR's Avatar
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    You guys are experienced and you may not remember how terrific it is to have someone reassure you when in doubt, because you are in doubt far less frequently than I am. Nonetheless, THANK YOU! It is my hope that some day in some way I might have a bit of useful info for you guys -- I doubt it but I'm grateful.

    I'm making another thread about seals etc. once I get my thoughts together.
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

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