1997 FORD FORD Engine And Engine Cooling Problems

INCIDENT LIKE MANY OTHERS I HAVE HAD MY 1997 FORD EXPEDITION XLT BLOW A SPARK PLUG OUT OF THE CYLINDER HEAD. THE VEHICLE WAS RUNNING FINE AND TROUBLE FREE WHEN A POP FROM UNDER THE HOOD AND A LOUD BANGING NOISE CAME FROM THE ENGINE HEAD. THE VEHICLE WAS TOWED TO THE REPAIR SHOP ; WHO IN TURN CALLED THE LOCAL FORD DEALER. THE REPLY WAS THEY NEVER HEARD OF THIS PROBLEM BEFORE. MY LOCAL SERVICE TECH SAID THE REPAIR KIT ALONE WOULD COST $1,000,00. TO REPAIR IT HE SAID THAT FORD HAD ONLY USED 3 THREADS IN THE HEAD THAT FAILED, BUT ARE NOW REPLACING THEM WITH A 7 THREAD HEAD., THIS TELLS ME THAT THEY ARE VERY AWARE OF THE PROBLEM BUT ARE WILLING TO LEAVE THEIR CUSTOMERS OUT TO DRY.. I GUESS THE SCARY PART ABOUT THAT IS I STILL HAVE 4 MORE 3 THREAD SPARK PLUG...