wow, that is not cool. Could it be a flaw in the unit, did you change brands or use the same type when you changed them out ?
Did the blow out occur in the same area on the cooler ?
What a mess, no I do know much, just throw out some questions trying to help. Most would say to much pressure for the cooler, or that a stuck solenoid on the return line causing to much pressure in the cooler.
Oh I should have said " my mind would have said those things to myself".
Not good Rex, and I am sure you have thought and went over many things with the first blow out. Your knowledge of what you did to that engine, wow, it just blows me away.
My mind is going nuts know wondering what caused it to blow out, here to learn all that I can.