Talked to the Ford dealer Service Manager. They already tried to make the repair using a repair kit for the F-150's (guess this happens to those quite regularily) and it wouldn't hold. Musta been a defect or wekened area in the head - the threads are still attached to the plug! Only other way to fix it is a salvage head. You know how it goes, the parts aren't all that expensive, but the $900 added on for labor is! Thanks all!
$900 for labour seems a little steep.. The reason might have been a dodgy coil pack. I had a situation where a dodgy coil pack created an ignition spike that created a ridiculous spark in my third cylinder which then caused a huge explosion and loosened the plug. Seems i got away lightly.
I have not heard this on the Focus heads but yes on the 5.4L. I had this happen to me twice on my Expedition to different heads. Fix the issue and spent three weekends ripping down the motor and rebuilding it.
The dealer cost was about 3K for one head. [paranoid]
I find it hard to believe it cannot be repaired. So the threads all stripped out....that's what a heli-coil repairs. The explanation they gave you sounds lame. The aluminum got weak/soft?
If your spark plug got loose......that certainly can ruin threads, and blow out a plug. I'd suggest a second opinion about the repair, after you call around to find a shop that can really fix the thing, without removing the head.
I know that when a plug gets loose, it leaks (naturally), and when it leaks, it gets fabulously hot- way hotter than normal, and maybe that's what degraded the aluminum to the point where the plug launched right out of there.
So maybe the aluminum has been degraded around the plug area and a heli-coil won't hold.