what condition might cause this to a spark plug?

[Pete M]

I'm guessing crack in the head right at the threads?

 

 

[pizzaman09]

I had a spark plug look like that on my project car.  I'm not sure what the cause was but I know it experienced excessive vibration, lots of oil in the cylinder, and maybe no power to it.

 

I could guess maybe it hydro locked in that cylinder on fuel?

[Eagle]

I've been wrenching for 65 years and I've never seen a spark plug that looked like that.

 

[AZJeff]

That’s a new type of plug failure I have NEVER SEEN, either in person or via photo.   And I have been working on cars for 55 years.

 

what does the plug hole in the head look like?

[Pete M]

don't know.   the guy was asking about replacing the head but hadn't actually pulled the head yet.  if I remember right, he said this has happened to the spark plug more than once.