New cobra- possible blown motor(blown out spark plug)

[Vr4me]

I purchased a 03 Cobra with 35k miles about 3 weeks ago. I drove it home from the dealership and parked it in the garage. Now, less than 100 easy miles later I'm limping the car home. It's running super rich and its making a sound that reminds me of a marble in a tin can. I'm depressed right now

Carl

 

[T-Pain808]

pull your plugs

 

[Emwun Garand]

Does your car have catalytic converters still? If the inside of a cat came apart and got clogged it could do this.

Is the noise for sure coming from the motor?

 

[Brutal Metal]

possible plug blow out, DON'T drive it til you take the coil pack covers off and inspect!

 

[timspony]

Bring the car back to the dealer!!! ...it should still have some kind of warranty!

90 days in NY!!

 

[MoKo_03SVT]

is there any way you could shoot a quick vid of the car while running/idling, so we can hear the noise? this would be much easier to help you diagnose, if we could actually hear how it is sounding.

 

[Vr4me]

Now that you guys mention it a blown spark plug makes sense. I fixed a F-150 a while back and it had the same sound and symptoms. I'm going to pull the plugs tonight and followup.

Carl

 

[Vr4me]

Now that you guys mention it a blown spark plug makes sense. I fixed a F-150 a while back and it had the same sound and symptoms. I'm going to pull the plugs tonight and followup.

Carl

 

[Jimmysidecarr]

An over heated engine will detonate and ping which will sound like a a can of marbles.

Is the car's temp gauge pinned or up on hot?

If there is enough air in the system sometimes the temp gauge does not even read hot ----yet you can hear it boiling away.

 

[Vr4me]

I confirmed it. The spark plug was blown out and the coil pack was damaged. Also, the spark plug for that cylinder had no gap. I'm not sure if it can be fixed now without replacing the head because someone attempted to fix it with a heli coil insert. I don't think it's a timesert.

The dealership offered to pickup the car and take a look at it but I don't know if I should trust them because either they didnt service the vehicle at all before it was sold or they attempted to temporarily fix it to get it sold. The car also had other issues that a mechanic should easily be able to identify and repair. I'm going to take the damaged parts to them and see how they want to proceed.

btw: I guess there is a chance the piston hit the plug. I'm not sure if there is anything else that would explain why there is not gap on that plug but I have a feeling the bottom is ok. I have a wideband installed and it never went lean. The oil pressure is fine, it didnt overheat and the other plugs look new. I noticed all of the plugs on the passenger side were over torqued (except the cylinder with the blown plug). I also noticed carbon or soot on one of the coil packs on the drivers side.


Carl

 

[postalbunny]

Look into timesert, they can be done with the head still on the car and are a lot safer than helicoil (no parts protruding into cylinder).

Pulling the heads off these cars usually involves dropping the motor, which is hard to do in a garage or expensive for a shop to do.

 

[AlwaysBoosted]

I would personally let the dealership pick the car up. This will protect you from them saying that you did this and that while removing the this and that. Unless you have some kind of certifications that qualifies you to do automotive work they will use that against you.

 

[Vr4me]

The car is going to a specialty shop today. It looks like the dealer is going to take care of it.

Carl

 

[timspony]

Good luck!!!!

 

[Jimmysidecarr]

The plug gap probably got closed up while the plug was bouncing up and down from the air pulses coming from the hole.
Every compression stroke it would have been pushed up in the plug well and then crashed down again, I doubt it ever contacted the piston.

Timesert is a good repair option.

 

[Bdubbs]

Can anyone explain to me why this happens? Just a loose spark plug backing itself off the threads? I check the tightness on my plugs atleast once a year.

 

[AlwaysBoosted]

Can anyone explain to me why this happens? Just a loose spark plug backing itself off the threads? I check the tightness on my plugs atleast once a year.

The first run of heads having only 4 threads for the spark plug is the culprit vs the later heads with 9 threads.

 

[03pulliedcobra]

The first run of heads having only 4 threads for the spark plug is the culprit vs the later heads with 9 threads.

Is that why they say (revised heads) for the 04 cobras?

 

[03pulliedcobra]

The first run of heads having only 4 threads for the spark plug is the culprit vs the later heads with 9 threads.

Is that why they say (revised heads) for the 04 cobras?

 

[cj428mach]

Is that why they say (revised heads) for the 04 cobras?

This is a really old thread but I'll reply and hope Brad doesn't smack me for it.

There are basically 3 heads for our cars

03 Cobra Heads with 4 threads holding the spark plug

04 Cobra Heads with 9 threads holding the spark plug

05+ "Revised" Heads with 9 threads holding the spark plug and the revised coolant passages in the head.

There were actually several more heads but this is the main differences between the heads. A pretty good explanation can be found here....
http://www.terminator-cobra.com/castings.htm