[rocky]

https://flic.kr/p/WVFGfS

Any help is appreciated. This is the 6th time I'm doing this job. The bolts for the fan belt tensioner mount keep breaking. I'm out of ideas. I have replaced everything. I've tried different grade bolts and even studs. I think the problem is with the metal surface you can see breaking away at the 2 bolt holes. If that's the case it will require a new engine as it is part of the block and not a cover. Any ideas or advice? The fan hub turns freely and is working properly. That's all this belt runs.

[00SSHarrison]

I tried to find some info on this but there is no service bulletins or any real info on this prob.
I worked for Detroit Diesel for 8 year (they build the MBE 900 and 4000) and another 3 now for Freightliner, ive worked on a lot of MBE's and i cant ever recall having this prob.
As for a fix i don't think going to a bigger bolt is a good idea but maybe a threaded insert with some bearing retainer might work, also is there a locating dowel on your tensioner?