06 GT, Automatic.

I originally thought that I had something loose inside my exhaust, but after removing it for a shake that is not the case. After really getting under the car while starting at it seems as though I have a buzzing noise coming from somewhere near the front-mid of the car that only occurs when I start after it sits for a few hours or longer and the RPMs swell and pass through around 1400 and when they fall again through the same.... I never hear the sound again until it sits for a while and then is started again. I have not experienced any kind of similar noise when driving the car.

It sounds to me like metal-on-metal contact somewhere but I have no clue where to start checking things. Curious if anyone could give me a place to start...

Here's some videos. In the first one the wheels visible are the fronts, so the camera is aimed at the firewall area...

Outside (Listen at 0:20-0:21 and 0:23-0:24 specifically)
http://www.youtube.com/watch?v=rnepdaredc0

Inside...
http://www.youtube.com/watch?v=-ixdsZikGtE

 

Can't tell much from the vid. Any heat shields down there? They are prone to rattling.

 

That's really odd. I've just started hearing a rattling noise coming from the trans/cats area too. It's driving me nuts, as I'm trying to locate it.

 

Torque your axleback and midpipe clamps about another 1/4 to 1/2 turn and also check the heat shields.

 

Really hope it's just something like this

 

Sounds to me like it might be the flywheel hitting the dust cover plate. There is a TSB for it. Mine does it but not bad enough to do anything about.

 

Hi everyone,

Rattling noises can be very annoying! If you are unable to determine the cause of your rattle, you may want to consider having your Mustang diagnosed at the dealer. They will be able to pinpoint the source of the noise. You can locate the closest one here. Please let me know if I can be of any additional help!

~Natasha

 

I believe that TSB is for manual trans? It's an automatic.

Also from what I've read there is rattling when the car is driving, in certain gears, ect. My issue is specifically on start-up, after that there is no noise...

 

I have that exact same rattle on my 06 GT 5 spd. It sounds almost like something is resonating? Mine does it on start up, but also at different rpm's while driving. I would love to know what it is.

 

I had the identical issue: metallic rattle at a specific RPM range (mine was about 1600-2000 RPM). Sitting in the driveway, I could gently rev up and down thru it and it drove me insane. In my case, it was the torque on the axleback clamps. Obviously there was a harmonic that made the mid-pipe to axleback mating surfaces vibrate.

Keep us posted.