rh71

'10 C300 with only about 14k miles - during slow turns such as on local roads or in/out of the driveway, regardless of forward or reverse, we're feeling a faint rumble when we turn the wheel before it even reaches full radius. Both directions left and right, both directions driving forward and backward, and ONLY WHILE IN MOTION. Leaving the car stopped with the wheel turned does not produce the problem. There is no vibration in the steering wheel at any point.

It is barely audible and more a feeling in the seats - like if you were to drive on those highway anti-sleep bumps, but not anywhere close to that severity. I want to say it feels like something in the rear but not sure how that would be possible. Visually nothing weird is happening at the belts. Any ideas?

As a history, we did have the original alternator replaced last year after it started making squealing noises. Apparently there's some noise at start-up now too but goes away quick, though I didn't hear it this time. Could this all be some drive-belt related?

Glyn M Ruck

Do you have Continental Sport Contact tyres? If you run your hand over the tread counter rotation do you feel any cupping or feathering?

Project C

I do run on those tyres

rh71

I don't have access to the vehicle right now to check but now that you mention it - we hadn't rotated tires at all. Due to low mileage, we've only done oil changes after 1 service A at the dealer 3 years ago. And I hadn't had to rotate tires on my other vehicle (uni-directional & staggered) so it's been the furthest thing on my mind.

I believe they are Conti's. Are the C300 sport tires uni-directional or staggered even in the slightest? Doesn't mention it on the C300 manual found on the web which isn't surprising. Should we be doing 2 fronts to the back but 2 rears criss-cross to the fronts?

Glyn M Ruck

Check the car. That rumbling is typical of Conti tyres on the W203 & W204 chassis the minute you have some wear & turn the wheel off centre. Fit Michelin PS2, PS3 or Exalto PE2 & the problem will be over.

Winker2112

Sounds like transfer case chatter. Usually caused by planetary gear set in transfer case. See a lot of them in the newer e's, c's and glk's. On lower mileage cars we sometimes drive around in figure 8s for 20 min to bed in the friction discs of the planetary.

Glyn M Ruck

Is this car a 4Matic?

rh71

Yes. Was hoping this was something common and simple to explain like tires. If it's a powertrain thing that would not be good.

Glyn M Ruck

Well you had better check your tyres & pray.

rh71

Could only look at the tires while still mounted today - they look fine, like new, even on the inner edges. Plenty of tread left all around. Ran my hand around and didn't feel any cupping of any sort. They are the stock 245/40/17 Conti's.

If it is this, what do you think the repair cost may be? Sounds like it's within the transmission - hope this doesn't mean they need to take it apart and rebuild. I think the powertrain warranty was 4 years which we've just passed in Sept.

Glyn M Ruck

If you run your hand counter wheel rotation over the tread do you feel zero feathering vs. the other direction? Most unusual for a Benz due to their suspension set up. Especially at the front with zero rotation.

Conti SC Tyres make a noise from new which gets worse with wear. I threw them off my W203 at 15,000Km much less 14,000 miles due to noise (like a bad wheel bearing) & rumbling when turning. Pity you can't borrow a set of wheels with other tyres mounted & try them.

If you are convinced it's not tyres then go & do many figure of 8's & see if this improves things as suggested. On 4Matics with transmission issues I'm always very aware that the noise is from the transmission & not the wheels.

rh71

Going to rotate tires tomorrow and see. And I'll check for feathering. Since it's a sport, it comes with "staggered" tires.

245/45/17 and 245/40/17. Would it be ok to swap them front to back anyway? The middle number is the profile size (sidewall)... shouldn't matter THAT much should it?

Glyn M Ruck

I presume you mean 225/45/17 & 245/40/17.

You can't rotate front to rear. Only across the same axle to change rotation. Once these tires are noisy rotation seldom helps. You really need to rotate approx every 8K miles to keep Conti's half quiet.

Winker2112

If it is a planetary gearset that is the cause, it could be costly. The back of the transmission/transfer case has to come apart. I would definitely bring it to a certified Mercedes tech though as outside shops have very little experience with this issue. Where are you located?

Khan28

I had the same issue and it turns out it was my TC. A TC fluid change took care of that and it's been fine ever since. It came to about $930 dollars by the time the Benz dealership did their inspections, test drives and the work but it was covered under the 6 month powertrain warranty that came with the car when I bought it. It may be different for your car because the transfer case setup is a bit different on a 7 speed transmission.

rh71

Just an update: we rotated both fronts with each other and rears with each other and the issue persists. As far as tire tread feathering, the rears had none but the fronts there was a little bit. We are just past the 4-year warranty (Sept. '13) but will likely go to the dealer for this issue anyway for the reason mentioned above. We're in LI, NY.

spyked

Good luck. Hopefully MB will goodwill the transmission replacement if its required. They are having too many 7G Tronic failures in the U.S.