Guess I gotta get in touch with Cklasse! This noise is annoying as hell! Sounds like a bunch of rocks or something inside!Only happens at initial throttle when I first rev the motor. After I'd say abut 1800-2200 rpm's there is no noise,but when the motor comes down off the revs at lower rpm's here comes the chain rattling noise and dissappears at idle.Originally posted by J Irwan
It also happened on my brother E36 M3.
The exhaust make rattling noise, so the dealer replace the exhaust underwarranty. After a few miles the noise present againt and finally they were able to determined that it was the cataylitic converter is the source. So the cat also replaced underwarranty as well.
The noise is very weak but it was there and become more apparent as you paid attention and listen carefully to it.
The noise occur only at certain rpm (I forgot what was it),
Although it wasn't a big of deal, my brother brought the car to the dealer and ended up with new muffler and new cat under warrantty
And looks like your technician is on the right path.
In US the manufacture should warranty any part associates with the exhaust/emission up to 80.000 miles.
I am not sure what is the law and regulation in Italy.
Hopefully the dealer will replace your cat for free.
Regardz,