Puzzle solved. It was actually just a split radiator hose, and the detonation was the symptom of a SUPER hot engine, not the cause. The hose split was hidden and right next to the overflow tank, which was wet, which led me to believe that the tank (which still had coolant in it) had overflowed. I should have recognized that the motor had not cooled down completely, but since there was still coolant in the tank I guessed that it was cool.
Amazingly I replaced the hose, filled it up, and it *seems* to be running great. Time will tell though

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1