i have a 99 f250 5.4 had a sparkplug blowout for the second time but this time the sparkplug looked like it was welded to the insert dose anyone know what might of caused the sparkplug to melt to the insert

 

i dont think i would worry a lot about what the plug thread to insert looked like. Your main goal is to get the insert locked into the head real good, then put the right torque on the sparkplug. Its hard telling what the plug went thru when the insert tore out of the head.

 

you will need a heli-coil these heads are famous for blowing plugs