DGS430

Hi - I have a 2003 S430 with just over 80K miles. I noticed lately that when I'm parked and I rev the engine, or as I am starting to drive, there is a crackling sound that seems to come from under the chassis. From what I can see nothing is loose. I recorded a voice memo on my phone but since this forum does not support voice memos, I had to create a link - here it is... https://vocaroo.com/i/s0RjZ6NRls7q
Any thoughts/comments would be greatly appreciated!

mercy-me

I followed link and listened. Sounds like one of the Cats the composite has broken loose to me. I had the same issue on mine. Get the car up off the ground enough to reach under and smack each Cat with a rubber mallet. I think you might find your rattler.

Good luck,

Bob

DGS430

Thanks a lot Bob! I will do that

lancelot1959

I have the same problem and I suspect that you're right, however, I'm wondering what you did after you verified where the rattling came from.

mercy-me

You have four options. 1) purchase a new front exhaust section which includes both Cats from MB for ~$410 + Shipping, see here 2) Have an an exhaust shop cut out the offending Cat and replace with an after market one, 3) replace both sides with a straight pipe for balance and 4) what I did here, (I gutted both sides)

Good luck,

Bob

DGS430

Hi Bob,

Thank you very much for this step by step - I was able to finally put the car on a lift and have the same exact problem you have outlined but just on the drivers side. If I were to gut the ceramic filter, wouldn't the check engine light come on and fail the emissions inspection? Did that not happen with your car after you got this done?

FYI, I live in NY state... I believe the emissions inspections differ by state, California being the strictest.

Thank you,

-Dean

DGS430

Nevermind, please ignore this question. I saw that these are rear cats that are past the Sensors. I have seen so many pictures and diagrams that I got confused.

DGS430

Hi Bob,

I have now been to 4 muffler shops and none of them have agreed to gutting the catalytic converter that rattles (as you have shown on your how-to write up) - their reasons vary from, its illegal, to its too much work, to the material in there is too dangerous for their health. Mind you, these are some of the sketchiest places that the Bronx and Yonkers, NY have to offer. I must note, that I do agree on the health concerns. Non the less, I am now considering two of the other options that you have outlined and would love your opinion.

1. Replace with just a tube ($50) - from what I have read in other threads, removing the rear cats, help the car perform better because of improved airflow exhaustion... since yours is gutted, do you think that's the case? While I would love to express concern about the environment and the benefits of having these rear cats, it just sounds hypocritical when you have a V8, so I will not.
2. Replace with generic cat ($150) - while I know that the generic cat doesn't cost $100, I am willing to over look it. Do you think this is a better solution than 1?

Of course both of these void the Core Charge cost savings if I were to order the part from MB or the parts website that you provided, should the front cats also go bust. What are the chances that the front cats would also break?

Thanks a lot Bob!