Did he tell you what the fix will be? Theyre prob gonna have to cut up the exhaust since getting to the valves wont be easy. Also depends on which valve it is,, the middle H pipe one or the one further back. The eurocharged guy said according to him the sound was coming from the middle of the car.

I’m having the same issue as well. I went on a test ride with the shop foreman happens around 3k rpm they are going to look into it again it’s been there a week. Sound goes away with valves closed.

I haven't gotten the car back yet -- they're working on it now... Will give an update of fix when I get it back.

There are 3 valves in the performance exhaust... 2 are on either side of the exhaust at the very end... The other is in the H-pipe in the middle section of the exhaust -- I suspect that's the one that's rattling. They'll probably try lubricating it from the outside... If that doesn't work, they'll probably replace the entire exhaust.

I've had this issue since I purchased mine. It's a defective butterfly valve. The head of service said he was going to fix it then told me he wouldn't because I removed my secondary cats. This is not the cause of the rattle but he said he won't fix it because of the modification. I am considering getting the exhaust module to just fully open the valves, assuming they won't rattle because they won't need to move. What really sucks is sometimes the valves won't open all the way and my car is super quiet.

That sucks that he flat out refused even though secondary cats weren't the cause. So its the valve in the H pipe then? What is the fix? Did you by any chance ask how much the fix would cost approx if you were to pay out of pocket?

Im really hoping my dealer doesnt refuse but the way they acted when they realized my cats were cut doesnt make me hopeful. It all depends on the SA, Eurocharged told me to go to a particular dealership which I will try if mine refuses.

I have the exhaust module and still have this problem... It doesn't control the H-valve... Nothing you can do electronically to fix the H-valve

I should get the car back tomorrow... I'll see if they can give me a quote for the price... Probably minimal if it's just lubrication... If its replacement of exhaust... Gonna be $$$$$

they tried the lubrication on mine but that didnt work. Also please ask them what the fix is...can that mid section not be replaced instead of replacing the entire exhaust?

I also have the exhaust module and can confirm even with the flaps open it still rattles away.

Yep, I had the exhaust module and still rattles.

Its because the ASR module does not control the butterfly valve in the H Pipe in the middle. If I can suggest a solution, can one of you guys find out if the butterfly valve in the H Pipe fail to close or fail to open? Meaning, if you were to disconnect the valve, are they springed to open in the fail state? If that is the case, you can take the connector out, and then use a simulator to terminate the connection:

https://www.rpiequipped.com/product/...ve-simulators/

Ofcourse this solution only works for people who are okay with this valve being open all the time. Other solution is for an exhaust shop to replace this H pipe with straight pipe instead of one with a valve. You only need to do this if the H valve is springed to close once disconnected.

If the dealership can't fix the valve for me, I may try the AWE simulator, but the problem is it could actually make the sound WORSE... The rattles only happens when you're on the throttle with the PE flaps on "loud" mode -- presumably that's when the H-Valve is OPEN... so it could be that the valve is unstable / rattling when the valve is OPEN... so if you put the SIM on the H-valve and keep it open ALL the time, you may experience the rattle not only from RPM of 2.5-3.5, but throughout the rev range... I guess we won't know until someone tries it haha.

I believe the H valve spring is set to open by default, not close. But as stated before, the rattling may only occur when the H-Valve is opening... Removing the valve with a straight pipe would certainly fix the issue =D

Unless the rattle is coming from the H Valve. I have never heard of the exhaust valves in the rear rattling. I thought the guys above confirmed that the rattling is from the H valve. If not then you are right, it would probably be worse.

Yeah I'm probably just confusing everyone with my wording. I agree that I think that the sound is coming from the H-Valves, but I am guessing that it only makes rattling sound while it's OPEN... which is based on yet another assumption that the H-Valve OPENS as you give it more throttle and that it CLOSES when you're off the throttle... now that I think of it, maybe that's backwards.. maybe it CLOSES on WOT and OPENS when you get off the gas.

Anyways... instead of just confusing people more, I'll just wait and see what my mechanic does and let you guys know what works if it works.

Know anyone who replaced H pipe with a straight pipe? Im curious as to how much of a difference that would make to sound since that is the route I will most likely take if my dealer refuses to fix the issue.

In Chris Harris's review of the C63s, he said the valve in the H Pipe is used to vary the tone of the exhaust sound throughout different RPMs. As far as I know the stock valves (All of them) never stay in the same position unless you use an exhaust module like ASR (No External Exhaust Module can control the H Pipe Valve). My guess is that you get the loudest sound with the H Valve completely open.

Just for trivia, The performance exhaust in the C43 has a H pipe in the exact location as the C63, but without a valve, just a straight pipe.

yeah it will def get louder but hopefully not obnoxious loud since ive gotten rid of my secondary cats as well. Thanks for the info.

The overall loudness of the exhaust is controlled by the muffler valves.

UPDATE: bad news for me.. Dealer refused to do anything. At one point he even tried to convince me that this sound is normal uh. Instead of replacing the H pipe with a straight pipe, do you think it would be better to maybe replace it with another H pipe except it wouldnt have a valve of course? No way do I want to spend thousands on a new exhaust!

When I said replace the H pipe with a straight pipe, I meant replacing the H pipe with just another pipe. I think it would be better not to eliminate the H pipe altogether. I honestly do not see the harm in that. Just do not forget to order the AWE Valve Simulator before you do that.

Another alternative is to find a junk C63s Performance exhaust for cheap. But honestly you can do that if you are too OCD about things.

And do not surprised about warranty. Mercedes is known for not being the best of pals for modded cars. You can try another dealership just to try your luck.

oh right so basically just replace the H pipe with another one without a valve in it? Im gonna go to an exhaust shop tomorrow and see how it goes.

Exactly!

Not very helpful to you guys, but got my car back and they used a specific lube for the valve and that seems to have fixed it for now... Will probably give it a good month before I install my cattless DP's in case the rattle comes back...

Nice. That lube unfortunately didnt make any difference in my car. Im waiting to receive my AWE Valve Simulators and then will be cutting out the H valve altogether.

Yeah I was kind of hoping the lube wouldn't work so I could get a more definitive fix... Hopefully the valve sim will work!! Keep us updated!

Mine has started making this noise on shutdown as well now. Wonder if it's a symptom of the same issue? :nix: