w210 knocking
MBWorld Fanatic!
Joined: Oct 2007
Posts: 1,564
Likes: 19
From: SoCal
98 Brilliant Silver E320 Wagon
If you pound the catalytic convertor with the back of your hand/fist and it rattles the catalyst has clumped up.
However, lots of things under the car (mostly exhaust system) can break a hanger or get out of alignment and rattle against the body. Part of the Schedule B service is to check the entire underside for such issues.
However, lots of things under the car (mostly exhaust system) can break a hanger or get out of alignment and rattle against the body. Part of the Schedule B service is to check the entire underside for such issues.
Senior Member
Joined: Sep 2009
Posts: 273
Likes: 0
From: Lincoln, NE
2002 Mercedes Benz E320
I have narrowed mine down to the driver's side near the rear door, I think. But that could be interference from my rattling muffler, so I'm not sure. At one point the rattling got so bad for a few minutes I had to shut the car off. It was loud, and embarrassing, and I was in a parking lot, lol. 
Weird thing was when the weather here was extremely cold (-10's to 20's), the exhaust made no noise at all. Completely silent.
Weird thing was when the weather here was extremely cold (-10's to 20's), the exhaust made no noise at all. Completely silent.
