blew a spark plug out!!

[cabldawg]

My brothe rin law's van blew a spark plug out yesterday. It seemed to me that the threads were ok in the head and I put a new plug in for him and sent him on his way. After hhe drove it about another 80 miles or so from yesterday and today it has blown it out again. Attached is a picture of the first one. What would cause this?

[b2_tim]

Adjust your focal lenght or put the plug on the ground.

Near as I can tell the plug is damaged. Looks like something smashed it, but the tip is intact. Strange.

[cabldawg]

At first I thought that the plug may have not been torqued down properly. I know that the aluminum heads are known for blowing out plugs if they are too loose. Now I'm really wondering. It appears to be that the threads on the one side are actually melted. The first photo was from my phone 2.omp Here are some from my camera 6.1mp.

The tip is missing on the plug that goes over the top of the electrode.

[b2_tim]

The pattern and slag look like a plasma cut, the slag shows very hot temps. I believe the hole in this head must be shot. It would be Interesting to see the other plug to see if it is the same.

Is there any evidence of the ground electrode left on the plug?

[cabldawg]

The ground electrode feels like it was snapped off. Where it protrudes from the base of the plug the metal is rough. It isn't smooth like a cut or being melted.

I asked my Bro-in-law if the other plug was still there. He said it was still on the wire, and he put it back in the head. I haven't been able to get back in touch to see if he made it home or not. He did say that the plug itself was intact.

[cabldawg]

I just talked to him He said that the plug seemed to be wet with oil, bt definitely intact. Sounds like the rings are now shot on that cylinder. There was no oil on the original plug.