no idea on what caused it...i bought the engine from a guy on a message board, and i'm currently rebuilding it.

the bottom end was spotless though...it came from a celica with an auto tranny there were no scratches on the crank and everything looked immaculate

the head, well, it looks pretty good for a 22 year old aluminum head.  the surface is flat, just a wee bit of corrosion in that one water jacket.  i figure it'll run a good deal longer before it needs another overhaul