Syracuse315

Took the car on a circuit track on Friday (photos/vids coming later) and ended up pushing the limit a bit. Thought I had a muffler leak or something similar, and after looking under the hood, found I have ripped the COP in half and launched the spark plug out of the engine. Here are some pictures:

Smashed the electrode in:


Crack in the ceramic portion:


COP broken in two:


In the process of getting a helicoil/time-sert because there are no good threads left in the block. I'm assuming this was my fault, because looking back at the torque specs on the spark plugs it's only 18 ft-lbs, and I'm sure I did tight + 1/4 turn...lesson learned!

The car felt a little hesitant under full throttle for about a month or two and my gas mileage has been much worse than normal. I'm hoping it has something to do with this issue of the spark plug slowly backing out of the head.

Fillerdust

That sux. I had that happen to me last year. I lucked out, I tapped it out and has held up fine even with dragstrip runs and some abuse, knock on wood.

Syracuse315

I'm worried that the damage on the spark plug was caused by hitting the piston. Either that happened, or just detonation when the spark plug was still somewhat in the head.

The shop is giving me a call today, so I'll learn the damage then.

uberstang1

That sucks, u can stick a scope into the cylinder and check out the piston.

Syracuse315

Found a bunch of $50 USB scopes, definitely picking one up soon.

TRexGAWD

Ouch, hopefully no further damage than just stripped threads..

cliffyk

The recommended torque is 11 lb-ft, this is from the 2000 Shop Manual:



Plug manufacturers usually say 13 to 15 lb-ft, or 1/16th turn for 14 mm tapered seat plugs; 1/4 turn got you up to 45+ lb-ft



If you have not already done so you need to remove and re-torque the other seven...

Syracuse315

Thanks for the info Cliffy. I planned on retorquing them as soon as I got the car back.

Here is the endoscope/inspection camera I just bought:

Syracuse315

And the videos from the track before it went boom:

Mustang Chasing Z06:

Syracuse315

And Z06 chasing Mustang: