Grinding noise

Tiny
JITHIN MATHEW
  • MEMBER
  • 2011 MERCEDES BENZ C300
  • 3.0L
  • V6
  • 4WD
  • AUTOMATIC
  • 76,000 MILES
Every time after I brake a little too hard, and then stepping on the gas gives me a grinding noise coming from the center of the car and also a whining noise. It will go away after a couple of miles later. I'm not sure if its the transmission even though it is shifting perfectly fine. I didn't get any error messages.
Saturday, December 14th, 2019 AT 3:03 PM

9 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This sounds like it is a transfer case issue. You have what is called a 4Matic AWD system. That means it is normally two wheel drive and then it applies the 4WD system. If there is an issue with the gear or clutch inside the system then it will grind while it is attempting to engage the system. Then it stops a mile or two later when it turns the system off and reverts back to 2WD.

The only way to repair this is to rebuild or replace it.

Have you recently changed any tires? With your system you need to change all 4 tires at one time. If you change 1, 2, or 3 tires it changes the wheel speed and will actually cause issues in the system.
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Saturday, December 14th, 2019 AT 7:43 PM
Tiny
JITHIN MATHEW
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No, I haven’t changed any tires.
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Saturday, December 14th, 2019 AT 10:38 PM
Tiny
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Okay. Then I suspect the transfer case is the issue. This is not uncommon for AWD vehicles so I would just be mindful of what makes this happen and try to drive in a manner that it doesn't do it. Eventually it will need to be repaired but if it is only doing by what you stated then I would put it off for a little while.
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Sunday, December 15th, 2019 AT 3:56 PM
Tiny
JITHIN MATHEW
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  • 71 POSTS
That is what I’m suspecting too, but I could hear that noise even when it’s in park after braking hard. I’m thinking if it’s the alternator bearing.
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Sunday, December 15th, 2019 AT 7:08 PM
Tiny
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Yeah. I would remove the belt and see if it still does it. Let me know what you find.
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Tuesday, December 17th, 2019 AT 2:28 PM
Tiny
JITHIN MATHEW
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  • 71 POSTS
I was driving it couple minutes ago and I didn’t brake hard or did anything to make the noise come back. But I made a turn really fast and it made the noise. I’m thinking if it’s the alternator. I will try to take off the belt.
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Tuesday, December 17th, 2019 AT 3:19 PM
Tiny
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Sounds good. Let me know what happens and we can go from there. Also, can we try to get a recording of it? Thanks
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Wednesday, December 18th, 2019 AT 2:53 PM
Tiny
JITHIN MATHEW
  • MEMBER
  • 71 POSTS
I took it to a independent shop and they said it’s the drive shaft bearing and transmission mount.
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Wednesday, December 18th, 2019 AT 3:51 PM
Tiny
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Great to know. However, is there a way they can get a part number to you for the bearing? I just want to make sure we get the info about what that is because I fear that is a little too general and we will get questions in the future about what that part is from others that have this issue. Thanks again.
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Wednesday, December 18th, 2019 AT 5:45 PM

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