Davi D

What's up mbworld,

​​​​​​Looking for some insight before the car goes into the shop for a diagnostic. There's a humming noise that starts around 40km and goes up as the car drives. I suspect it's the tranny due to its inevitable failure, but wondering if it could be something else. It definitely sounds like something is spinning as it fluctuates with the car speed. I'm bracing for the worst but hoping for the best.
Will update this thread as I find out info. Any insight or similar situations?

Thanks!

416mOe

I wouldn't jump to conclusions with your tranny... it could be something as simple as a wheel bearing... my front left bearing failed at 85k kms.

Demvang

This ain't a domino effect where other cars' transmission fail then yours does as well. I also lean towards the wheel bearing. With that speed, shift to Neutral and see if you still hear that noise.

Davi D

Thanks for the replies, any idea how much a bearing costs at a dealer/indie shop?

416mOe

paid $300 to replace mine but mine is a 4matic so a bit more labor involved.. this was at an indie btw

Davi D

Mine is also 4matic. I'm starting to think it's the transfer case but I'm gonna get a few opinions. Where'd you get yours done? I'm also in the 416 and Mercedes wants $400 for a diagnostic which is a little steep to tell me what needs fixing

Davi D

W204 gurus,

My mechanic has told me a whining sound is coming from the back of the transmission, not the front. I suspected the torque converter was the culprit but it seems if the noise is near the back, the torque converter probably isn't the issue due to it being near the front.

Any insight or similar issues with other members? The car is a 2010 C300 4matic with 156000 kms.

Also, does anyone think doing a tranny flush would remedy the problem? Maybe some new fluid could lubricate the bearings. The car starts making noise around 40km an hour and keeps going with the motion of the car. It does not fluctuate if I gear up, just maintains with the motion of the vehicle speed.

Any insight would be great!

ItalianJoe1

Rear of the trans could be a transfer case issue since it's 4-matic.

Nobody online will be able to tell you where the noise is coming from, us guessing doesn't help. Take it to someone who can accurately diagnose it.

Davi D

I'm telling the community that it's coming from the back of the trans, not asking where it's coming from. Just wondering what part of the tranny is the back where bearings might deteriorate.

This thread can also be used for future members who might have similar issues find an alternative then going to Mercedes and spending 7-10k on a replacement tranny that, unless services are being performed 100% properly, their transmission will very possibly fail.

I appreciate the insight though

ItalianJoe1

Start with the transfer case. There's multiple bearings inside the transmission, unless you open it up you won't be able to differentiate where the noise is coming from and why.