spark plug blowout

Green Machine

Green Machine

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I drove up my 97 yesterday morning and it was running fine. I shut it off and it cooled down for about a half an hour and then I started back up. All of a sudden there was a loud pop, smoke, and the motor was missing. I shut it off right away. Smoke was coming from the back of the drivers side head. I had tools with me so I removed the cop cover. The coil on cyl # 8 was laying funny and the boot was tore In half. Shined the flaslight down the hole,

Spark plug was in the right place. Then I got plug wrench on the plug and it just spun freely and wiggled. Pulled out plug and the electrode was pushed down to the platinum and the insulator was gone. I thought oh !#*@ .. so then i started it back up and limped her home.
Anyone else her have experience with a blown plug? Helicoil time I spec. :(
 
it happened to my Gen 1 about five years ago. Happened on a long trip. glad I had most of the tools with me.

As I was drivin on the interstate, I smelled gas entering the cabin. Didn't think much of it. Thought it was the old truck ahead of me. So I thought it could be the Mark. Pull into a station, pop the hood and smelled gas but nothing I could see after 20 min of looking. Back on the road then Boom! Engine was missing bad. Pull off the interstate into a park.

And there it was. #4 spark plug blew out. No damage elsewhere but Busted the plug cover.
 
I am not used to seeing the plug ground strap and insulator get demolished, but I am used to seeing this happen with the 2v 4.6/5.4/6.8 and there is nothing to contain the plug like the covers on the 4v. I would have at first suspected something more sinister happening, but probably not, other than wondering where the insulator made its way to.

I am glad that in the other thread the OP posted the end results.
 
Bangster said:
I am not used to seeing the plug ground strap and insulator get demolished, but I am used to seeing this happen with the 2v 4.6/5.4/6.8 and there is nothing to contain the plug like the covers on the 4v. I would have at first suspected something more sinister happening, but probably not, other than wondering where the insulator made its way to.

I am glad that in the other thread the OP posted the end results.
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The insulator went out exh ports it will not pass thru the cats thou. Sometimes the insulator can get caught right under a valve and seat when it closes bending the valve head some.
 
OchoMarko said:
I had a plug blow out on my 89 SHO and pulled over and reinstalled the plug and it never had problems again til I sold it.
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then it didn't blow out, it just came loose. and, the SHO has a lot more plug threading than the mark does too.
 
Told my mechanic friend what had happened.
he came over with an insert kit. He then reamed out the plug hole and installed the insert.
I picked up a new coil boot and a new plug and I was back on the road in 45 min. Charged me $75 bucks. No damage from plug blowing out.
 
Happened twice on the town car, second time I upgraded to motor with 7 thread heads.

Not a bad price for the fix, doesn't happen to often on Marks. Can't remember how many threads are in B heads.
 
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