Today while driving I started hearing this intermittent noise from the rear of the car. Every once in a while it will sound like a drier full of nuts and bolts spinning and then this distinct 'clunk' like dropping a bolt in a metal pan. Then all will be quiet for 15-20 seconds and the process will repeat. It sounds like it's coming from the muffler but it's hard to tell. It happens regardless of vehicle speed, engine speed, gear i'm in or if the clutch is up or not so I don't think it's a driveline thing because it'll do it when the car is stopped. No abnormal sounds from the engine either. It's not the fuel pump because it's disconnected since I'm using a mechanical one. Only thing I can think of is something got into the muffler and is getting knocked around.

Any ideas? It's really annoying.

 

Do you have a catalytic converter?

 

I'd check the cat too.

 

I don't have a cat. A friend of mine said the muffler's broken apart. The exhaust hasn't gotten any louder though, it's odd. Guess I'm goin muffler shopping which is kinda good cuz this one's been annoying the neighbors. I like how the (gasp!) 5.0 Mustangs sound, who makes one that sounds like it?

 

the mustangs sound that way cause of the engine and the true dual exhaust. i kinda like that sound too, but ur never gonna duplicate it.

 

Did you check your rear swaybar links? I had one that was broken, and it appears from your description of the sound, to possibly be the same thing I experienced...

 

it's not the swaybar links because the noise happens even if the car is standing still.

oddly enough, the noise seems to have gone away and the exhaust is now quieter a little, go figure. whatever was rattling probably got wedged somewhere