RadDad

Howdy Gents,

I've got a 2005 C240 4MATIC wagon and I've got an intermittent growly sound that occurs on every drive under certain situations:

1. Bring the car up to speed in neighborhood settings (25-35 MPH)
2. Lift off gas to decelerate to stop sign
3. At some point around 28 or 29MPH I hear a gravely/growly/low humming sound approx under the center console
4. The sound passes in micro seconds and doesn't occur again when accelerating

Perhaps related but I hear another sound at highway speeds when coasting, regardless MPH:
1. Occurs anywhere 55-75MPH
2. Lift off gas
3. Very slight, almost imperceptible low noise
4. Get on the gas and the sound goes away

I almost always drive in complete silence so maybe all cars make the second sound but the first one is very concerning! I did some reading on the STAR CD this morning and I couldn't find any service bulletins about the noise but I did see that the driveshaft has flex discs and a center bearing.

Are these sounds typical of bad flex discs or center bearing?

Thanks, as always, for your help!!

zpbarnett

I own a 2003 C240 Wagon and have experienced strange "console located" noises. Crawl under and see if your sound abatement matting is touching the drive lines/components. That was my case:

https://mbworld.org/forums/c-class-w...ump-thump.html

RadDad

Thanks for the tip!

Looking through the epic "All things transmission" thread I got the idea to reset the trans. I followed the instructions on a couple of YouTube videos and successfully reset it. I then took it out for a spin and the shudder/growl did not occur at the usual places.

It does make a little noise at that one spot, approx 30mph, coasting (foot off gas) from high gear.

I think the issue is related to the 5th-to-4th downshift as the reset transmission makes this down shift quickly when before it seemed to be indecisive about wether to downshift or not.

I've ordered fluids and filter and going to do the big flush and see if that cleans things up even more.

RadDad

I flushed the trans over the weekend but still have the noise. Drat!

I do feel great about the flush though. There was no metal or any sludge on the magnet or in the pan. The first few liters I pumped out were opaque but still red and it didn't smell any different than the fresh stuff.

Further reading on the web identified a service campaign that could affect my car - the transfer case shudder at low speeds:

http://ww2.justanswer.com/uploads/EU...7_campaign.pdf

Putting in my VIN on M-B's website does not show that my car is affected however.

Other service texts and advice I've read indicate a drain and refill of the transfer case is in order so I'll be getting under the car again this week.

Question for the fluid knowledgeable: Does the transfer case take the same ATF as the trans, Fuchs ATF4134 in this case?

LILBENZ230

Check the transmission mount. That caused noise from that area in my 05 C230.

RadDad

Thanks LILBENZ230, I will check that when I'm under there. Looks like the crossmember has to come out.

Can anyone confirm the fluid question? Is it the same ATF as in the trans?

akssdd

Take a look at your vibration dampeners along the driveshaft also. They are pretty damn thick but could potentially dry rot etc.