friscoaves

I recently started noticing something strange with my 01 s430. Sometimes(not always, but especially on downhill slopes) i hear a pretty loud rattling noise coming from my undercarriage. What could this be? It only happens as the engine is revving itself back down, never when revving up and it sounds as if something is rattling around in my exhaust or something, anyone know what it might be??? btw, car only has 50k miles if that helps at all.

mleskovar

Common problem when cats come apart internally, sometimes mufflers as well. You can find out by banging the cats and mufflers from beneath and if anything is loose inside you'll hear it rattle.

friscoaves

is that a major problem or somethin I can ride on for a lil while? Also, what would be the solution to the problem...replacing the cat converter and/or the muffler? and how much would somethin like that cost me? thanks a lot for the help!

fixer

Hiya,

I just throwing in my pennys worth, but if it is the Kat, then I would suggest a replacement asap. The reason for it is that if the Kats are breaking up, there will be particles that can be drawn into the engine which will damage the cylinders.

If there is damage to the cylinders irreprable damage will be caused and an engine strip/replacemnt engine will be required.

My advise would be to have the issue investigated and resolved asap, i.e. drive straight to a workshop.

Regards

mleskovar

Usually just an annoyance but depending on what comes apart it could be worse. Muffler baffles have been know to block the exhaust flow and make the motor run rough or stop it. I haven't heard of loose exhaust parts getting sucked back into the engine but anything is possible. Until you find the rattle you won't know what it is though.