the plot THICKENS!(as more info arrives from the fellow that
suffered the failure eMails me)

1) the bolt in question is an AFTERMARKET (Fastenal)
M10X1.5X3- fastener marked * 10.9 ^ on the top...

I had shipped the young man THIS:
http://www.brickboard.com/FAQ/700-900/B234Ftimingbelts.htm
(scroll down about midway to : "OIL PUMP BOLTS" )

2) LocTite red high strength applied (and I fancy he did more that
"just a dab'll do ya") as evidenced by the "half shank long RED
witness stain"...

3) he did the torquing per the "Brickboard thread" I sent him

so far so good...now it turns UGLY

4) he HEARD THE RATTLE and dismissed it as A/C CLUTCH CHATTER
(NO washer was employed)....

5) he is now gathering up stuff for the SECOND BUILD

my surmise is:
1) I *TRULY BELIEVE* the bolt to be correct for the application
2) I believe he failed to adjust for the "lubrication of the LocTite"
(thus adding a higher stress load into the bolt)and / or
got the torque ABOVE spec somehow
3) I think he did the damage on install and the tenacity of what remained of the
"shank" shows correct "invisible hurt"...the portion just under the HEAD
shows the ORIGINAL STRESS FRACTURE and the "inner stain" is evidence of
the VIBRATION SHEAR FAILURE....

I'm going to make him do a "spark test" to see if he can verify the hardness
(it wouldn't be the FIRST time that a *counterfeit fastener* made it's way into
the supply chain)....

I'll keep you updated..and I *would* like to hear from the "metals wizard"...their insights (even if only to confirm your suspicions) is INVALUABLE info!! (which I would like to file in the "horror show files" to be shared w/the hapless "have to do it again"
crew)....

Thank you for your help and thanks to all the guys on BB who posted thoughts / ideas...will let you know what our young friend discovers when he showers the shop w/SPARKS!!

all the best from the gearhead ranch in norte carolina...

Mick