03 cobra 8# piston slap spark plug

[5_0coyote]

Ok guys so i was cruising and all of a sudden i heard a pop then ticking. Thought something was wrong with the motor but when i got home and checked the spark plug the plug was pushed out of the head and the head is stripped. Anyone have a idea how this happened? plus how to prevent this from happening again. And what do you guys think i should do now? Thanks oh and mods are pulley mid pipe catback and the car has 52k miles. spark plugs less than a year old to.
BUILT DATE-11/20/02 idk if that helps but owell.
Now i don't think piston his spark plug.

 

[hotcobra03]

Maybe you have the 1st head design with 4 threads vs 9.

An insert will fix for now..

 

[5_0coyote]

Maybe you have the 1st head design with 4 threads vs 9.

An insert will fix for now..

Thats what i am thinking but when you say for now you mean it can happen again with other plugs or same one? And do you think it was detonation or piston slapped the plugs?

 

[hotcobra03]

My guess was plug wasnt tight from the start..

Cant see piston hitting plug..

See cobra bobs info on heads..he put alot of time into it for use..

Its expensive to just remove head have it fixed for more issues..

The most recent head might be getting hard to find..I was lucky and had just did mine when cost of head was 1100..now might be over 2grand..

I had issues with valves on that head only..both 1st and 2nd..I got about 200k on 3rd design and its been fine..

Its strange I got 4 thread on passenger side@370k with no issues

 

[cj428mach]

Like hotcobra said 9 threads would help. I dont know if anyone has any real evidence that 4 threads aren't reliable if plugs are torqued correctly.

I just replaced the heads on my 03 to repair the head tick. The drivers side head was still available in March. The passenger isn't available any more.

I put the new 2005 revised head on the drivers side and had a 04 head rebuilt for the passenger side. My car only has 9700 miles on it but I figured if I was pulling the motor to fix it I was going to upgrade both sides to 9 thread plugs.

 

[5_0coyote]

Like hotcobra said 9 threads would help. I dont know if anyone has any real evidence that 4 threads aren't reliable if plugs are torqued correctly.

I just replaced the heads on my 03 to repair the head tick. The drivers side head was still available in March. The passenger isn't available any more.

I put the new 2005 revised head on the drivers side and had a 04 head rebuilt for the passenger side. My car only has 9700 miles on it but I figured if I was pulling the motor to fix it I was going to upgrade both sides to 9 thread plugs.

SO the problem is the spark plug not tight enough?

 

[Brutal Metal]

^ Yes detonation and the piston slapping had nothing to do with the plug backing out, it happens to these cars, I have a timesert in cylinder #7 on mine..

 

[DSG2003Mach1]

the threads on the plug will get ruined as the plug backs out and starts rattling around then finally ejects itself. Odds are if you listened closely before it happened you would have heard what sounded like an exhaust leak as it blew past the loose plug. I would definitely check your other plugs