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Old 06-22-2021, 05:18 PM
oldskewel oldskewel is offline
Join Date: Nov 2014
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Originally Posted by Russianblue View Post
this is the crux of it. the BENZ bolts would seem to take a lot less time to implement. I do have a bit of time pressure here unfortunately. but not a TON.

i'm not finding much detail on the Mercedes solution though. among other things... which bolts to use and obviously a verified TTY method. i mean, if you are stretching those bolts to spec, it's going to take a good bit more torque than the stock setup. now you've got two bolts clamping harder than the others. i was originally thinking just use the MB bolts in the repair holes but that might be a bad idea. would probably need to do all of them. so the TTY issue might be a deal breaker in that it takes as much time as timeserting 3 or 4.

so...i suppose the next step is to torque those head bolts again tonight. 40NM + eyeball 90 + eyeball 90. I know i am missing a washer btw...good catch. it disappeared somewhere under the car. I'll find it.

after that, lift the head off and check block and head for warpage. i think this budget is only gonna work out if my existing head is repairable and i can get it skimmed and tested for $200-$300, which i THINK i can. i know i can prob find a junker head for cheap and put all my parts on it but i've rebuilt a 12 valve M20 head before and that's no fun at all.

btw oldskewel, i tried to PM you yesterday to ask you some questions about your experience (namely, re-timing the cams/vanos) but your mailbox is apparently full! i'd love to hit you up with some questions.
Regardless of the repair method you choose, I'd do the same thing to all 14 holes, keeping things symmetric. That will also make it less critical regarding how you torque them.

Somewhere on this forum, I think there was a little discussion about what the resulting torque (e.g., 60 Nm as a guess) on the stock bolts following the TTA sequence (40 Nm + 90* + 90*) would be. If you know that number, and the bolts have been TTY'ed (that strain hardens them), you should be able to then reinstall them to the same torque, in theory.

Considering the M11 bolts, if trying to replicate the stock setup, I'd aim for the same final torque - i.e., the 60 Nm number, as that should give the same clamping force. Any yield will be different, and maybe they won't even yield at all due to the extra diameter. The thread pitch (1.5 mm) is the same for the stock M10 or the replacement M11, so the relationship between final torque and final axial tensile force on the bolt (= clamping force) will be close to the same.

The M11 vs. M10 means each bolt will then be a 20% stiffer (121/100 approx area ratio) clamping spring, so the desired compliance in the design will not be there - one reason to use TTY is that the strain hardening means you can get the same strength from a thinner bolt, and the thinner bolt means (easier to fit, but also ...) it is more compliant, which is needed to keep even clamping pressure as the engine fires and thermally expands.

The fact that so little (only that one thread) of block threads came out, you're in much better shape than most for trying the M11 solution. For threads that pull out full segments of block material, the hole is already at least 10mm wide, leaving not much room at all in those areas for an M11 thread to grab into.

I would not underestimate the time required for TimeSert. And it is not a slam dunk. @ahlem reported problems doing it the first time and came in and re-did things with the BigSert alternative, I think. No doubt that @Effduration can do it as he says, but that's specific skills and experience vs. someone doing it the first time.

Slight difference in your plans vs. what I did - I took the option to remove the exhaust manifolds with the head in place. Then my kids helped me lift the head off. No Hazard Fraught engine thing for me when you've got helpers.

I did get an email notification about your message bounce, so I cleared a few messages. Feel free to try again. Sorry about that.
2001 X5 3.0i, 203k miles, AT, owned since 2014

Last edited by oldskewel; 06-22-2021 at 09:29 PM.
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