RW> ATF mixed with coolant (coagulating) probably didn't have enough time to   
   RW> circulate through the core, thus building up a pressure head at the   
   RW> weakest point in the system...upper hose.   
      
   That is exactly what happened.     
      
   RW>  MH> The overflow was also overflowed.  :)   
   RW>    
   RW> The only pressure relief point. 8^)   
      
   What is strange, is the overflow's cap didn't pop off.  The entire overflow   
   tank is plastic, too.  The thick upper hose ripped in half, however.   
      
   After I opened the overflow's cap, it was completely full to the top with that   
   goop.  Normally, the antifreeze is at least 5 inches below the top of the   
   overflow.     
      
   - Mark   
      
   --- WWIVToss v.1.50    
    * Origin:  http://www.weather-station.org * Bel Air, MD -USA (1:261/1304.0)