There was no indication of a problem last time the vehicle was driven. This morning when starting there was immediate clang/grind sound and rocking of the vehicle. Motor oil began leaking below the vehicle. I have photos of the leak.
I would first appreciate it if you can confirm the location. I believe this is the engine block, being the lowest portion of the engine, just above the transmission case.
In the below photo, the break is near the top edge, to the right of the bolt head.
Is this break on the engine block?
What would be the likely causes? (It does seem like this was caused by impact of a broken moving part, and not the usual combustion?)
It would be interesting to know how often this might happen. Seems like a really rare problem?