Hi y'all, first post here. I guess I should've been here a while ago since I care a lot about my car and try to understand and do most fixes on my own. But this time I really got it bad. Here's a pic of my troubles:


I started noticing the misfiring Saturday night, but didn't understand what was happening. Come Sunday it got worse and worse. Monday I drove to work and dropped it off at the mech (Aamco) and here's the result. So now they're telling me they need to remove the head since they've already tried putting another spark plug in there and the thread in the head is not holding it down. Has anyone gone through this before? What might cause something like this to happen?
FML...

 

Does it look like exhaust gas has melted the plug wire?

The plug may have been loose in the threaded hole resulting in exhaust gas damaging the plug.

On very rare occasion a bad plug can leak gas between the ceramic and steel body.

Spark plugs have come out of cylinder heads before and damaged threads on aluminum heads are not uncommon.

It might be possible to repair the thread with the head still on the engine, this would save repair costs. This is not uncommon but requires a little more skill. The spark plug tube may have to be removed to get any tools needed for the job close to the hole. The hole drilled and taped for a Helicoil (or whatever is currently used today) and the coil installed.

Given the high labor costs for removing the head suggest you explore the above possibility. Might require finding another shop.

Suggest you ask about stripped thread replacement for this specific engine (would need the year and if V6 or 4 cylinder) at the Toyotanation website. Where this has been discussed before.

An internet search should turn up hits as the one below:

http://www.popularmechanics.com/auto...o/4212608.html

Depending on the engine miles if the head is going to be off might consider a valve job or at least changing the valve stem seals.