Jimmy_c63s

Wanted to ask you all, when travelling highway speeds over 60mph (100kmh) and letting off the gas pedal to coast, do you guys hear a very slight "woooooo" sound when decelerating? It's not a bothersome noise, sounds like it's a transmission sound. It's been there ever since new.

It's barely noticeable if you're listening to music etc but it's there.
When you accelerate it'll go away. Anyone else notice it?

Wooooooo

amg8

From your description, it does indeed sound like the tranny. I hope it isn't the same issue one of the Youtuber "Mike" had with his C63s. What happened to him was after the transmission oil change, he started getting similar noises in the tranny. It turns out the dealer put in the wrong tranny oil (too thin or too think can't remember exactly). They had to replace the entire tranny for him as it caused damage.

Jimmy_c63s

Thanks for the reply and info. So when you're driving on highway speeds over 60mph and you let off on the accelerator, you've never heard a "woooo" type of humming/whine before in your c63s?

It's a very subtle noise. I don't know how to explain it and I doubt a video could pick up the sound.

It's almost like the sound of straight cut gears but 1000 times quieter and only happens over 60mph and letting the foot off the accelerator

amg8

I have not heard any unusual deceleration noises as of yet. Knock on wood. When you let off the gas, did it auto downshift and then you hear that or is it staying in the same gear and you still heard it?

Jimmy_c63s

Nope! It's only when in 7th gear at highway speeds above 60-70mph when I gently let my foot off the gas it'll be there.

Happens every time. Are you sure yours doesn't do it too? It's very un noticeable but it's there!

untamedd

no such noise on my end

amg8

I don't think I heard anything but I will go out today and test it again to see. Just to be sure so I can simulate your exact setup, what drive mode are you in? Also are you sure its not the sound difference when you let off the gas and it goes into "sail" mode? This is assuming you have "auto start/stop" enabled and in comfort mode.

Jimmy_c63s

That would be wonderful mate, thanks for helping me out there.

For me it's in Comfort mode, Exhaust loud and ECO off (so no sail mode).
7th gear 60-70mph then lifting foot off gas pedal, coasting it (speed reducing slowly but still in 7th), i'll hear a whine like straight cut gears type of "woooo" but very subtle.

Wonder if you'll hear it too?
Dealer reckons "they all do it" and it's a sound from the transmission. But they always say that with everything

NYCSoiL

Turbo spool may be? I hear it a lot in my car

Cascade1

Yes! My 19 does this, I wanted to ask but didn't know how to describe it. I have downpipes and blow off valves installed but this definitely sounds like Tranny. I hope it isn't bad. I'm almost due for 10K service so I was gonna have them take a look.

Jimmy_c63s

Mate, I wish I could hear my C63s spooling. I can only manage to hear it with all windows down and flooring it with the exhaust on "quiet" mode

Yes! Finally, some one else who can confirm this. For you, does the whining "wooooo" noise disappear when you start to accelerate a bit? Then appear once you let off the throttle?

Which gear does yours do this in? I swear, it's hard to describe it but it's like a "weeeeeee" or a hooooo" noise but VERY subtle. Like straight cut gears whine.

Cascade1

It happens when I'm being sort of soft on the throttle but still picking up speed and there's no boost, I lift off gas and immediately get that whine with the engine brake. Yes if I get back on throttle the noise is no longer there. Also if I'm hard on gas and theres alot of boost I dont hear it, but this could just be because the car is very loud above 4-5K rpms with boost

amg8

Hi Jimmy_c63s ok so I've tested it several times yesterday based on the settings you mentioned and I don't hear a peep when letting the throttle go at 60, 65, 70 and tested 80 as well just to be sure. I tried it in eco mode and non eco mode. I hope that information helps.

Jimmy_c63s

Man, that's spot on. I'm so relieved you know exactly what that sound is. Whine on engine brake!

Thank you very much for taking the time to try it on your car! At least that confirms that some of our cars do it, but sounds like most of them don't.

I will be getting the transmission and diff fluid changed this week so will report back if there's any difference

Go Dawgs

Yep, my car does this and it isn't even a 63..
Definitely the same sound though based on your posts.

Jimmy_c63s

Yep, you must have the same thing too! I think most people think it's turbo related! But I've actually heard this identical "weeee" sound in a car we've owned in the past. Never had any issues from it in the other car.
Hoping to see if there's any difference with new diff and transmission oil this week.

I've stuck my head all around the cabin trying to find out where this noise is coming from and I am certain it's from the transmission or diff area. How about you? Is yours coming from the front footwell/center console area too?

notbadgoodsize

I have a whiney noise but only hear it on engine brake in the higher rpm. Always thought it was the engine. Will check again later.

NYCSoiL

I hear a turbo spool if letting of the gas pedal between 2k and 3k rpm. “Whine” noise

Jimmy_c63s

Spot on. That's the noise.

How long have you had the noise for?

raudiace4

Lol is this your first turbo car OP?

Jimmy_c63s

No.

George_1992

I can confirm, I also have this noise in the C63s Coupe. I would call it a high-pitched bearing noise, but unnoticeable and it is only present during engine brake (foot off the gas). It has nothing to do with turbo or induction from what I know.

Regards
George Lisciandro

Jimmy_c63s

Update: Engine oil, transmission oil and diff oil changed last week and it didn't make any difference. The subtle whine is still there during engine braking/coasting at high speed.

So it's not fluid related. I would say it's just a sound that comes with some, if not all, of our cars.
Mine has had it since new (3 years now) and never had any issues

Jimmy_c63s

A year later, car still seems to be running well 🤷‍♀️

This almost inaudible whine sound is like the sound of a bad ground on stereo speakers. Same sort of frequency but a lot quieter and more mechanical so to speak.

The whine noise comes dead on at exactly 69mph (111-112kmh) only. Never any time else

🤔

Being the paranoid type I started looking at replacement diffs and getting quotes here and there.

I still wonder if anyone else hears this in their cars, too?

George_1992

My coupe makes a OOO noise/WHINE (sorta like blowing through a bottle top sound) at EXACTLY 45kmh (27mph for USA) also around highway speeds above 60mph............

Anybody else with coupe have that??? I think it's the diff 😤😤😤