kLeos

I get this really loud humming noise when my sunroof is open and I drive above 50mph...
Is there any way to fix it or is it a common problem?

HellsAngel

im no expert, i fixed mine 3 days ago at a local shop, but u can start here :
https://mbworld.org/forums/c-class-w...ars-fixes.html

California

No, I think he means when the sunroof is open at a certain speed the wind comes through and causes a vibration that sounds like a humming noise... it is NOT, as far as I can ascertain, a mechanical problem but a wind problem...

or that's MY problem on my coupe.

Anyone else know what this annoyance is all about?

LinDenKid

Having a pano-roof on a coupe is annoying. LOL

California

Thanks for the info.

It's actually great having the glass roof, just sounds terrible when you try to drive with it open. Funny that it took someone else complaining about it for me to remember this annoys me, too.

I'm under extended warranty so guess I'll try to complain. It works great mechanically.

tommy

It's normal, imho. I've never heard of anything being done to make it better. Other than turning up the radio, of course.

MW_ATL

I had always assumed that little hump on the glass of the front portion was to make some change in the wind pattern and reduce that noise. I'm guessing that's not right, huh?

I've never tried STT to find out what that little thing is for.

tommy

No, you're right. I've always heard that it does much reduce the wind buffeting, and never much about noise reduction, though I guess it would do both, if it does one.

I just got a new sunroof, and still no hump, which is fine with me. The more wind, the better. My hair will always have that just-blown dry look.

California

On my 1980's VW Rabbit, I bought a cheap tinted bubble thingie that covered the front portion of the sunroof. It fit on the front with sort of a curved piece around and over the top six inches or so of the sunroof.

Something like this would actually solve the problem. I think it was a VW part or VW third party add on. I recall recoiling at the 35 dollar price tag.

Midnight Koop

the little hump is a wind deflector and it is suppose to redirect the streamlines to keep a continuous flow over the car:



otherwise, air would enter the sunroof causing more turbulent flow over the top.

i have the same problem and noticed that at certain speeds there is a "tone" that the open sunroof makes, and i think that it is not the best design. if i drive just at the right speed it can get very loud just like blowing into a large coke bottle. BUT... if i drive either faster or slower than that speed it goes away.

There is actually more than one speed that this happens relating to the sound harmonics and its annoying. Just adjust your speed (faster or slower... i recommend faster) to avoid it

hope that helps

Midnight Koop

sort of something similar to this... but i realize this is a convertible.

kLeos

the humming wind noise is no match for the radio
it gets so loud at times, it is basically impossible to drive with it open, unless you want to go deaf

I'll record a video today with my camera phone

kLeos

weird... it didn't make that much noise today, even when I was going around 80 on the highway

My car was on the sun the whole day, dunno if that had anything to do with it...

Just ordered the repair DVD manual from mercedes

I shall investigate further!

Dr.Fox

I've heard this noise as well on mine (now my Pano works, woohoooo! ), and I think part of the reason why the humming noise exists is because that front wind deflector that raises up isn't really fully doing it's job.
I think when you go fast enough, that stream of wind that is supposed to be redirected over the sunroof opening ends up hitting the sunroof itself, or even coming into the car (making noise). I think that wind deflector, at high speeds, needs to adjust to a steeper angle in order to allow that wind stream to "make it" to the rear of our roofs, rather than hitting the sunroof itself, or whatever else is causing wind turbulence/noise.

Just my wanna-be-aerodynamics-engineer .02

kLeos

You are actually right, I just watched Transformers Revenge of the Fallen, great movie btw , and on my way back, I drove with the sunroof open, it started making the noise , and I pushed the wind deflector down with my hand, held it for a few seconds and the noise was gone!

Now the question is, how do we make it so when it opens, it sits at a steeper angle, like you said.

MW_ATL

I always figured that was what the little hump was, but never knew if it actually helped or not. I discovered that putting your fingers up in the flow at that point helped with the harmonics, but it never bothered me enough to worry about.

Yep, it appears (for me) at about 45 mph and reappears at about 90...and should (I'd assume) reappear at about 135. Changing speed by just a bit either way solves the issue.

slammer111

This is old news. It does this around 70km/h when the sunroof is fully open. The problem is when the airflow over the car doesn't make it quite over the open sunroof, and ends up buffeting/vibrating through the cap between the roof (ie rear panel) and the open glass panel.

There are several fixes.
1. Close sunroof slightly. You'll notice that each position of the sunroof has a "sweet spot" that causes this buffeting noise. Adjust as needed.
2. Open a side window a crack.
3. Retrofit a glass deflector with one that has a hump. Looks like MB recognized this as a real problem, so they made a new OEM part. ($$$)
4. Make your own "hump" to minick the MB solution. I used a $2 black rubber "door guard". You wouldn't even know it wasn't OEM.

Johnsct

I have never owned a car with a sunroof that didn't do this. I have found a spot when opening the sunroof that diminishes the noise and buffeting. It's still there, but it's bearable for me. My wife can't stand it.

Jeepin Al

This is a good thread, I too have the same problem. Slammer 111 could you post the part number or a picture of the "improvement" that will stop the vibration? If it takes a cheap stick on door guard to stop the noise that would be great.

I thought maybe it was the rubber gasket at the front of the deflector, and if you pull the deflector down the noise does go away. I was going to disconnect the arms that raise the deflector and just let it sit there limp. But if there is a fix

I tried the sunroof in all positions, once the noise starts, it will not go away until it is almost closed, at least on mine. Windows opened closed or cracked a little. I happen to like riding around, especially at night, with the roof open, what PIA with the noise.

So if you cold please post up the fix I think it would be greatly appreciated by all that still have some of our hearing left

jsmith18

y family has 3 C coupes, 2-2003's and a 2002. One of the 2003's is a late model and has the little wind deflectoor on the front glass piece as do all 2004's and on. The buffeting noise from the other two was awful and I made a small wind deflector from a rubber door guard that I purchased from an auto store. Its about 3-4" long and does the job well. I attached it to the glass with good quality double sided tape. Its been on for two years in serious winter and summer weather and car washes without a problem. Ordering the updated glass from MB will be very expensive.

slammer111

Not the best pic, but here you go guys.

Any thick rubber strip can do the job in theory if glued down. And yeah, I used a rubber door guard. I would recommend some good glue though, as mine flew off on the highway during a really hot summer.