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Old 11-04-2020, 04:44 PM
oldskewel oldskewel is offline
Join Date: Nov 2014
Location: SF Bay Area
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Originally Posted by ahlem View Post
My thought is to use a 1/2" steel plate and shorter bolts and test torque all the locations to 50-60 ft-lbs (or the spec) and be sure nothing else is going to cut loose when I reinstall the head...
Really sorry to hear of the problems you're having with this. I feared this same thing on my M54 and consider myself at least a little lucky to not have had any problems. Decision making here must be tough, so I won't try to give advice on the major decisions here, but on a specific issue ...

Regarding "the spec," I just want to point out that the 40 Nm + 90* + 90* (this is the spec) will be accurate only if a new (not yet stretched) head bolt is used, and also the height of the bolt head above the cylinder head is the same as when the head is installed. So you'd need to put a spacer in there matching the depth of the head, if you want to try to do it to that spec. Probably not worth trying to do all that carefully.

Better to just torque to a set torque value, without the additional angle. Yours + @Effduration's 50-60 ft-lb suggestions sound good to me.

From my notes, the Bentley, page 020-4 says an M10 class 10.9 bolt has a torque spec of 66 Nm (49 ft-lb). So that's the torque before any yield occurs. When the actual head bolts are torqued, they do yield, so it will be higher than that. So that's why I think 50-60 ft-lb sounds good. It should definitely hold at 50 ft-lb, and you might worry a little as you turn it up to 60.

Definitely worth testing every existing insert like that before proceeding. You want any problems to appear now vs. later.

I agree with @Effduration's other comments.

And BTW, what you're going through here is exactly why I would have gone straight to the BS inserts if I had known about them, gladly renting @Effduration's kit with the jig, etc. Of course checking on proximity to cooling channels, but I figure TimeSert and others would have blown through those if it were a likely problem here ... vs. the known problem of weakened block material, and the imperfect precision in TS installation that will happen when you do it with the block in the car, without a jig (how I did it), vs. out of the car and on a milling machine. I don't know how close I was to having the problems you are, but I might have been very lucky and right on the edge.

On the sizes, the head bolts are M10, the TS inserts are M12, and the BS inserts are M14, all with 1.5 mm pitch. From that youtube proof testing video I posted a few posts up, the BS inserts were far stronger than anything else. "The ringer" as the video guy called them.
2001 X5 3.0i, 190k miles, AT, owned since 2014

Last edited by oldskewel; 11-04-2020 at 04:51 PM.
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