Hi fellow W220 owners,

This morning as my wife went to warm up the car I heard the most disturbing noise from my 2001 S500. It sounded like a rattling noise and with no idea where it's coming from I decided to explore. With minimal experience in noise recognition I was at a lost. I also notice this noise whenever we com to a stop and then take off at low acceleration.

Does anyone have a clue as to what/where/why/how this came to be and any sugestion how to eliminate this? Any suggestion is greately appreciated and thanks in advance..

Could be number of things, here are some simple stuff you can check for:
Make sure your belt is still on.
Turn ac off and see if there is a difference.

Check the link below and read sections about motor mounts, cats and harmonic balancer.
https://mbworld.org/forums/s-class-w...tart-here.html

It could also be your catalytic converters starting to go bad - especially if it sounds like it's under the front driver and passenger seats.

Secondary cats. I could almost bet money on it. Mine did the same. It was a metallic rattle at idle/low revs. sounded like a ball bearing in a tin jug.

I just had the secondary cats removed and a straight pipe installed in place of them. Car runs completly fine and sounds no different, well other than the rattle is gone.

and no error message ?

I bought the OEM reman part from my local MB dealer for $576. Other dealers were quoting $1000+ for the part because they didn't know about the the reman part being available. It was OEM Mercedes and bolted right on. I had my indy shop install it for $90.