Exhaust Rattle C63S coupe.
Not sure how much truth there is in what I have been told but apparently they use a special grease. Given that exhaust temps can exceed 1000 degrees (at the dump pipe), you might need to refresh that lithium grease fairly often. Might want to try high temperature grease instead.
Edit: Sanity check on the last thing because I remember hearing it years ago... "Our research shows the crossover pipe is generally good for a few horsepower, the torque curve generally comes in earlier and the sound drops between 2 and 6 decibels. In most cases it will also take that dreaded highway drone and convert it to a purrrrrr. That’s a lot of benefit for one small modification."
Last edited by illuzn; Jan 6, 2020 at 09:41 PM.
One could say it sounds like wastegate chatter.
On the C63s it is spot on 3rd gear and gradually accelerating. It only seems to happen at the exact revs that were mentioned by others. I do wonder if permanently closing the H-pipe flap will disturb the car's balance?
Regards
George Lisciandro
If you are out of warranty, you can either upgrade to an AWE Switchpath exhaust or if you don't want to, you'll need to weld the H-Pipe flap and plug in a AWE simulator to prevent the engine from going into limp mode and throwing a CEL (Check Engine Light).
You can try to grease it but I don't think it will last long.
What I want to know is if the H-pipe is welded shut, will it disturb the car's balance, performance or cause droning? This is why I'm reluctant to do this. Perhaps @untamedd knows?
Regards
George Lisciandro
Last edited by George_1992; Jan 30, 2020 at 05:53 AM.








The Best of Mercedes & AMG
I'm looking at cutting out my H-pipe, blocking it off and plugging in the simulator too. Do you think getting the H-pipe closed off would create drone or ruin the sound of the performance exhaust? This is the only thing that's worrying me.




Last edited by PaulC63s; Feb 9, 2020 at 12:36 AM.
Had the same fu**ing rattle on my 2016 C63s coupe and it was crazy annoying
My MB dealer here in Russia didn't help me so I decided to "tune" my exhaust.I made my C63s catless (bought downpipes) and just pluged OFF H-pipe valve and made it CLOSED forever by welding it in closed position. So now I have very loud exhaust and no rattle!
The only one problem is CEL error, but gonna fix it by going Stage 1 or Stage 2.
Hope it will help someone! Greetings from Russia
ps nada malo en tratar de hacer que se vea como acciones como sea posible, pero el concesionario se verá en la soldadura y decir que no es la acción de modo que eso es algo a tener en cuenta también. [/ quote]
Hello guys . same problem in my car. and I have started reading this great Forum that thanks to you things are easier. I also want to cut pipe H but I'm not sure where to cut it and if the motor that closes and opens the valve, does it have to stay there or disappear? it will give me error and I have to buy the AWE simulator? thanks
I had the rattle start after my secondary cat delete and only with the performance exhaust button turned on (the loud button). Only ever heard it with ~30% load, in 2nd and 3rd, between 2k and 3k revs, going both up and down through the rev range. I could make it happen in 4th at those revs but only using about 60% throttle.
I was hesitant to have the H pipe welded shut as I expect it does more than control sound (could be wrong), so I had my mechanic pull out the valve, lube with high temp grease, heat and stretch the spring holding the valve and putting it back together (1 hour all up). The valve doesn't just bolt off - it is more of a pull to remove it. Sorry, I didn't take pictures while he was doing this cos I was too busy looking under the car at my front tyres which are due for replacement at 12,000kms (f&*k).
After 2 days, there is still no noise (I will keep the group updated if it comes back). I suspect the spring stretch provides some additional firmness which is what it needs so that the butterfly valve doesn't flap under those ~30% load conditions.
Hope that helps.





Please tell us how you go!

I think you're onto something with the "spring stretching" technique because when I lightly did this on mine I noticed the rattling noise completely disappeared for two weeks (but returned I'm guessing because because I didn't stretch the spring too much).
Last week my Mercedes dealer ended up doing the standard lubricate on all of my valves. I'm out of warranty but they did it for free, and it has been fine. They're really good at the dealer I go to in Miranda, Sydney.
If it comes back, I'll stretch the spring on my H-pipe valve even further.
There's a TIPS DOC G149.10-p-064223 regarding the issue and is well known by Mercedes-AMG so even if you are out of warranty they will sort it out.
Last edited by Jimmy_c63s; Jun 8, 2020 at 05:39 AM.








Heading back to Mercedes again this month to assess the ongoing rattle from my H-pipe and this time they will try to do a "goodwill" (out of warranty) case for me to get the part changed instead of just greasing it. I hope Mercedes will do the right thing and honour a replacement.
After the grease failed to fix my issue I was thinking of just buying it myself and applying it whenever needed but at $120 AUD per tube (part no. A0009899151), I don't think so.
The alternative product for this is Castrol Molub-Alloy Paste TA but I can't find this in Australia anywhere.
Anyway, I'll report back here in case others have this same problem in future.
PS: Here is the paste that they apply A0009899151
Heading back to Mercedes again this month to assess the ongoing rattle from my H-pipe and this time they will try to do a "goodwill" (out of warranty) case for me to get the part changed instead of just greasing it. I hope Mercedes will do the right thing and honour a replacement.
After the grease failed to fix my issue I was thinking of just buying it myself and applying it whenever needed but at $120 AUD per tube (part no. A0009899151), I don't think so.
The alternative product for this is Castrol Molub-Alloy Paste TA but I can't find this in Australia anywhere.
Anyway, I'll report back here in case others have this same problem in future.
PS: Here is the paste that they apply A0009899151
Thanks!!!
My mechanic put me on all three flaps yesterday, grease he uses on his race car.
The noise is gone.




Last edited by Jimmy_c63s; Aug 23, 2020 at 12:26 PM.
And his dealer is Liqui Moly, so I imagine he uses from that brand.







