Under body rattle/pinging when car is in drive. on 1998 Mercedes-Benz E320

Pronounced when backing up driveway, and periodic when car is idling in drive, or when accelerating from a stop. Do not hear sound when car is in park. Sounds like pot metal rattling. Any advice is greatly appreciated.

by in San Francisco, CA on January 25, 2014
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2 answers 5 comments
ANSWER by , January 25, 2014
Have the catalytic converter checked as it may be broken. You can raise the car (use appropriate safety measures when under a car) and firmly tap on the catalytic converter, if it's your noise you'll here it every time you tap the converter with your hand. Be sure the exhaust system is cold, you don't want to burn your hand.
COMMENT by , January 25, 2014
Thank you for taking the time to share your advice Mercedes Connexion from Cupertino, CA.
ANSWER by , January 26, 2014
Don't take to dealer ,its the heat shield rattling ,u could take to local shop ,they strap it up or just discard ....or a muffler shop or me but I'm to far away..... Dealers going to hose you ,tell you ,you need the world . I think if it was a bad catylitic converter ,it would set check engine light..
COMMENT by , January 27, 2014
That's very good advice, Steevie. Thank you. There's no dummy light lit on my dash.
COMMENT by , January 27, 2014
I hope its a heat shield but I've never seen one loose on a 300 yet. The catalytic converters break inside their housing on a regular basis (the honeycomb seperates from the outer casing, hence the rattle). Usually the left side for some reason. I've had cars come in with broken cats and they usually don't set the check engine light as the honeycomb is still doing its job-just noisily. I've even had them fail emission testing because they are inefficient and still no light. Let us know what you find, I'm curious.
COMMENT by , January 27, 2014
Hello Mercedes Connexion: Thanks for your follow-up re: the light on the dash. I need to get the car on a lift and do as you suggested in your first reply. That will help resolve the issue. I'll definitely let you know how it all sorts out. Much appreciated...
COMMENT by , January 27, 2014
I'm sorry then it's like the jeeps that do that , Yes , I know , ok ..