Additional note: If both bolts were to back out of a cap, the first would drop through the hole. The cap would hang from the second bolt until it dropped with the bolt to the bottom, hence one bolt remaining in the cap.

Perhaps the main cap adjacent to the broken rod beat the @#$% out of the rod as it was flailing around, hanging on that last bolt, trying to drop. If the bolt had bent, it would no longer freely back off, and the loose cap would just hang there, beating up on the end of the rod.

Edited June 9, 201410 yr by FastWoman

The picture is as was when opened. I believe too that the bolts backed out of the main cap (one cap completely and the second cap had one missing, one loose). It doesn't explain to me why the bottom of the piston, where the wrist pin goes, was broken completely away and the piston not tipped to one side. Once the skirts were broken off I'd have thought the pin would have pulled (or pushed) the rest of the piston unevenly and it would have turned sideways and crushed into the head. I tend to think the initial failure was in the wrist pin, putting a harmonic distortion in the crank which caused the bolts to come out of the main caps. Never the less, will be a great JB Weld experiment.

Any chance you could take a look at the bottom edge of the cylinder? Still curious about what caused the rod to punch a hole in the block.