Sirs.,

I Have a '08/09 C63 AMG and it has not given me any trouble so far. However, in the past weeks, I've noticed two things that have changed.

First one: the car is making a rattle sound, especially when I'm driving over bad pavement, such as paving stones. It is a metallic rattle, and is not constant. It sounds a little like if I left some metallic piece inside a cooking pan, and would shake the pan. Like hitting a metal trash can lid with a fork or spoon...Ok, I'm out of metaphors, but I hope you get the picture. My office parking has a very steep ramp and sometimes I cannot avoid to scratch the bottom of the car when entering it. I believe it could be related to that, but I’m not sure.

Second one: a very strange burnt smell. It almost smells like over burnt barbecue. The first time I smelled it, I thought my neighbors were cooking meat at 8:00 AM. But then I smelt it again at the office parking, and then again at home. And I don't believe the whole world is making barbecue. It only appears when the car is hot, and is especially strong if I've driven it hard.

The smell is only noticeable when I am outside the car. If I'm moving with the windows down, I cannot smell it, and if I'm at a traffic light with the windows down, the smell is aaaalmost unnoticeable. The rattling is only audible with the windows down too, but it is pretty hard to miss this way.

THERE IS NO NOTICEABLE PERFORMANCE LOSS. I'm not saying there isn't a loss, but I could not notice it under normal driving conditions.

Since both “defects” appeared at the same time, I would bet they have some relation, however, it could be also plain bad luck. Anyone would have a guess before I take it to a repair shop and get ripped off? I have no modifications. Car is completely stock.

 

Both issues you described happen to me before.

The burnt smell came from a plastic bag that got caught on my secondary cats. If you're smelling BBQ, it might be a small animal caught underneath your car. Raise your car on a lift and thoroughly inspect your undercarriage and exhaust system.

The rattling noise on my 09 C63 was cause by a bad engine mount. The way it was explained to me was, our engine mounts have hydraulic fluid in them. One of my mounts busted and the fluid leaked out, causing a rattling noise over bumpy road conditions. They were replaced under warranty. Even if you have only one bad mount, they should both be replaced. Hope this helps.

 

I got that metallic rattle. It annoyed me for quite a while. Then I remembered I throw change in that weird rubber recepticle thingy in the center console.

 

Good advice above, also check heat shield that is loose and could be vibrating, and any plastic touching any hot exhaust...

BBQ could be indeed animal flesh...just apply some Sweet Baby Rays and go to town...

 

that stuff makes everything better

 

I had a rattling sound. The tiny metal "brace" toward the back of the exhaust system holding the two sides together was loose and rattled.

 

lol! as an aside, i noticed a knocking sound in my cabin over rough roads. ended up being the passenger seatbelt buckle hitting the plastic seat trim (with no one in the seat). just something to file away in the rattle database.