Knock, Knock. Who's there? Your cylinder head. Oh, that's not a funny joke.

[MustangChris]

hm. an over-heated piston could very well be a culprit. ..... thanks for the heads up on that! If i dont find anything under the valve cover, that'll be my next step.

as for unplugging the spark plug, I already did that, as stated in the OP. Both Spark and fuel were pulled from #4 and the sound still remained.

 

[BigBore96]

My mistake. I overlooked that part. If it were mine I'd suspect a couple things like previously stated being a valve issue, melted piston, or a wrist pin working its way out. I've had it happen in my old mustang and it was a high up tick/knock that was louder in the head @ #8 though you could hear it in other places. Just not as loud. Was annoying as it came and went depending on driving conditions and rpm.

Hopefully you get lucky and it turns out to be a simple fix like a busted follower.

 

[MustangChris]

hm. ug. a wrist pin, eh? .... .. ...

i need a new hobby. anyone want to start an underwater basket weaving forum?

 

[JeremyAlan]

LMAO @ the new forum idea, make a video Chris!

 

[MustangChris]

Of the knock or me weaving under water???

 

[JeremyAlan]

I lol'd. Of the knock good sir.

 

[MustangChris]

okay. ill get a video tomorrow.

 

[JeremyAlan]

waiting...

 

[MustangChris]

i know. We just got it back over to my apartment and I forgot my camera in my buick.... >.< lol.

ill try with my cell phone.

 

[JeremyAlan]

buick eh? that your daily?

 

[jexey]

You have to crack it open, it's the only way dude. Rashes on the cylinder wall maybe, more likely something like a loose wrist pin which would explain why you can only hear it under stress and certain RPMs

 

[MustangChris]

yup. buick is the DD. :-/

and here's the video!!

http://sn95forums.com/showthread.php?53755-2004-Cobra-Cylinder-4-knock