Why is it always the #7. That's the one that went in my truck too!!!!!

 

Looking at the motor this morning I found that the top of the piston has welded to the cylinder wall. I guess the piston cracked and stuck between the head and the rest of the piston and punched a crack in the cylinder wall and water jacket.

 

that sucks! sounds very familiar though. burned it about at the 10 or 11 'oclock position didn't it? are you sure about the wall being cracked?