jctevere

Hey guys & girls, Happy Easter!

Anyway, I'm just posting to report a rather annoying issue I have uncovered in my c300. It appears that everytime I tilt the moonroof up and have all my windows closed my ears pop and the interior cabin pressure gets all screwy. The issue is so bad that my subs sound like they are busted and produces very un-clear sound like cheap a toyota sound system. All of this seems to happen around 47-53 degrees... It is a very odd issue and I can replicate it 100% of the time within those temperatures. Problem is fixed either when I close the sunroof (which will cause my ears to pop again and sound system to be fine) or if I open another window... I find this issue very very weird, anyone else have the same problem? I have never experienced this in any other car...

Carsy

Physics. Opening the sunroof sucks the air out of your cabin creating a vacuum . Having a window open prevents this as the air is allowed in from outside. Air is pretty dense at those temps.
You have sussed out how to operate it yourself by opening the window first.

C300Sport

I have felt changes like that in the past but it has generally only been at highway speeds and not very pronounced. I have never noticed the stereo being affected. Is this an aftermarket sub you are talking about? If so, may have something to do with the install??

jctevere

Nope, stock base audio system, not the upgraded package. Didn't screw with anything. I expected the cabin pressure to change slightly when I open the moonroof, but I think this is kind of extravagant, must be a design issue or something? Literally it sounds like my bass on the radio blew and you hear almost rattles.

In fact the first time I thought that is exactly what happened until it went away when I closed the moonroof. It is actually very disorienting and hurts the ears pretty bad. Somewhat disappointing to me as I LOVE to drive with the moonroof in tilt position. I hate now having to open another window to let the air escape, Blows me out of the water now with all the wind on the highway or just driving around...

As I said, I can tolerate ear popping or whatever, but for my sound system to sound like garbage is a bit too much... This has never happened with any of my other cars... Odd, was wondering if anyone else experienced this or if it is just me, and if it is just me, is there a fix?

Additionally, while somewhat on topic, I also hear a bit of a wind whistling from my left ear occasionally. Some have dismissed it as the side mirror wind noise, but I think there is a gap in my driver side rear window. Or is the wind in fact that loud from our "elephant ears" =P

C300Sport

OK, I understand you now. Almost every car I have ever had has the "flutter" turbulence when you open the roof and no other window. Unfortunately, it is just something you will have to deal with on the C Class.

samkim4986

I just bought a used 2013 c250 and I have a very similar issue. Whenever I open any of the windows in the car, especially at hwy speeds, my ear pops and feels like there's a lot of pressure in my ears. It usually gets better when I open another window, but sometimes it gets worse. It feels like the pressure is weird even with all the windows closed at times. Did you ever find a solution? Does ANYBODY know a solution? THANKS

LAS2511

I'm having the same issue with my car. I just bought a 2012 C300. Did either of you every find an answer to this??


Thanks!

Carsy

It's simple ...:- https://en.wikipedia.org/wiki/Bernoulli%27s_principle

Just spend a little time reading this .

Funkwagen

This isn't an issue, it's a characteristic of a car with a sunroof, that has door and window seals in good condition

michail71

Physics FTW!

LAS2511

I understand the physic of it now, so thanks! I'm just concerned from health standpoint how safe it is to have your eardrums exposed to an increase in pressure (to the point of popping) every time I hit the A/C button. It even effects the acoustics within the car, its very bizarre.

michail71

While uncomfortable it shouldn't be too bad. Pilots and divers get exposed to conditions like that. It can be a problem if you have a ruptured eardrum or congestion.

When I open or close my sunroof on the highway I contract the muscles that open up the pathways to the middle ear. I really hate that last bit where the sunroof closes up, lol. I can even feel pressure changes from driving over hills and overpasses when the windows are down.

Oh, this is something many car owner's manuals will even address.

dieseldoc

I agree. Very normal.

LAS2511

Just wanted to let you know my recent findings. I spent 4 hours at the dealer's body shop trying to find the "body exhausters" I was told about by Mercedes-Benz. There are two vents located on both sides of the rear bumper under the taillight. They are only visible from the outside if you remove the bumper completely. In my particular case, these body exhausters were replaced and body work on the bumper, and they were put in upside-down! This cause almost no air to flow out of the car and hence the extreme increase in pressure and ear popping. I literally flipped them over and put them back in and my issue is almost completely gone. The only issue I still have is one the highway at high speeds or if the A/C is on full blast. Hope this helps!

michail71

That is interesting, I would have not expected that. Thanks for posting.