mercedes s430 exhaust sounds really bad as if somet is knocking?

Question

mercedes s430 exhaust sounds really bad as if somet is knocking?

Answer 1

If it sounds like loose marbles, the usual cause is that a catalytic converter has begun to break up. The cats are probably covered under the MB pollution control warranty. However, they will be very reluctant to replace it until it completely fails. I guess you can take comfort in the knowledge that once they begin to rattle, they will soon fail and thus be eligible for free replacement.



The other likely problem is a loose heat shield, of which there are several. Get it up on a lift and inspect with ears and eyes.

Answer 2

Its one or more of the catalytic converters. These are covered by a 8 year 80,000 mile from original new delivery warranty. However mercedes will only cover for rattling if the Catalyst Sound Analyzer on the SDS picks up a strong enough signal. Its ridiculous but Mercedes has been trying to avoid paying for cats under warranty using this method. If you do have to replace take comfort that Cat prices have dropped in the past month or 2.

Answer 3

It may be one or both of the main catalysts that has broken apart internally and is now rattling. As mentioned above, they are covered under the emission warranty so check with your Benz dealer to see if that is the problem.

If it is not the catalytic converter, it may be one of the exhaust brackets or a loose heat shield. Either one of those two things could also cause a bad knocking/rattling noise.

Answer 4

There is a central resonator assembly that can knock if not properly affixed to its mounts. The same with the rest of the exhaust. Get the car on a rack. You want to take care of this in case there is an exhaust leak as well as the loose parts. That can be extremely dangerous and as we head into colder weather can be fatal.

Answer 5

check the rubber bracket hangers and see if one missing causing it to rattle .(they look like little black donuts) or you if you dont find anything external, you have a rod issue ! not a good thing. knocking is not a good thing.. the odd chance that the muffler has failed inside too... some exhaust leaks will give the effect of a knock too. good luck with it.

Answer 6

Exhaust is not properly attached. Check brackets.

Answer 7

check to see that the rubber exhaust mounts arent perished or missing check to see if the exhaust isnt blowing if not....ENGINE PROBLEMS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!