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2008 E300 4Matic
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161 Posts
Hi everyone,
I have a 2008 E300 4Matic with 220K Kms (around 138K) and in great mechanical shape.
I don't know if this is the right thread but I would like to ask if anyone knows about this. Basically, I started hearing a faint humming noise if I release my foot off the pedal and the car decelerates from 90Km to 80Km (55-50 miles) and then the sound disappears. The sound only happens when the car is left to decelerate between these two speeds. Not before, and not after! A friend tells me it might be time to change the differential oil. Can just this be the case? If so, should I change the oil in the two differentials (front & rear) as well as the transfer case?

I am DIY inclined and already did several small-medium jobs including a complete ATF exchange on my 722.6 transmission last month, so I could probably change the diffs oil myself.

Your feedback is highly appreciated.
 

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2007 E350 4matic
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10 Posts
ezzo,
Can you isolate if the noise is coming from the rear differential or the front differential?
 

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2005 E320 CDI *black on black with nearly every option*
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989 Posts
Do a transmission flush if that hasn't been done yet, and then get back to us
 

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2002 C230 Sport Coup and 2006 ML350
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1,126 Posts
Certainly replacing the fluids is your 1st defense.
If you still have the noise, your next
move is to get the vehicle on a lift with the
engine running and wheels spinning to pinpoint the
problem.
 

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2008 E300 4Matic
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161 Posts
ezzo,
Can you isolate if the noise is coming from the rear differential or the front differential?
It is definitely from the rear differential and always when car is decelerating (noise starts betwen 90Km/h to 80Km/h) only.
 

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2008 E300 4Matic
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161 Posts
Certainly replacing the fluids is your 1st defense.
If you still have the noise, your next
move is to get the vehicle on a lift with the
engine running and wheels spinning to pinpoint the
problem.
I'd appreciate if you pointed me to the DIY thread for the differential fluid flush.
 

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2007 E350 4matic
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10 Posts
This problem is inherent on most Mercedes 4matic's around this year because of faulty spec'ed bearings.
 

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2008 E300 4Matic
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161 Posts
This problem is inherent on most Mercedes 4matic's around this year because of faulty spec'ed bearings.
Ok. This explains it. I changed the transfer case fluid a few days ago, and the two differentials' fluid a couple of weeks earlier, and I still have the same noise. Sigh!
Which bearings are you referring to here?
 

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2009 E350 4-Matic Sedan Sport
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2 Posts
I read somewhere either on this forum or another that this model is prone to differential problems. MB used undersized bearings. My 2009 E350 4 matic has the same issue, 2 shops indicated rear diff needs replacing. Not worth getting a salvaged one as they typically wear out between 80-120K miles (mine lasted 140). Theres a guy on Ebay that sells upgraded bearings but good luck finding someone to rebuild the diff. My quotes for factory remanufactured unit, installed, ranged from $3200-$4200. Anybody have this work done or success in finding someone to rebuild it?
 

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2007 E350 4Matic
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3 Posts
I did the job myself after buying the parts from the ebay seller you referance (inertia pro). It's a very straight forward job that any shop could handle. I am not a professional mechanic although I do have a lot of experience. The seller is very helpful with tips and I'm sure he'd be willing to speak with your mechanic if they had questions. If you do it yourself you'll need a heat source (oxy-fuel or oven) and a freezer but no press or anything like that. Also you'll need to get all the seals from a dealer or one of the online places. Been about 6k miles since I did it and it's great. Quiet and smooth as new.

Good luck!
 

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2008 E300 4Matic
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161 Posts
I did the job myself after buying the parts from the ebay seller you referance (inertia pro). It's a very straight forward job that any shop could handle.
I tried to search for a seller named inertia pro on ebay.com and could not find any. Can you share a link to the seller's page?
 

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2007 E350 4Matic
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3 Posts
Hi Ezzo,

Sorry I didn't respond - if I'm not messaged directly then it doesn't come to my email. Gald you found the bearings though and that posting in particular - he was super helpful in when I was getting ready to do the job.

By way of an update - It's now been more than a year ( or a year and a half) of driving and all is still good. In miles it's probably around 15,000 at this point. No troubles at all. Please don't be intimidated by this job. Anyone with really basic mechanical knowledge and a free day can do it!
 

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87 300D 5 speed
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5,406 Posts
There are currently 148 w211 differentials for sale on eBay between $130-600 including shipping. This is a non issue.
 

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2007 E350 4Matic
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3 Posts
Ezzo,
I just read what I could on this forum and anything else I could google and started the job. I did talk to the guy who sells the bearings (inertia pro on ebay - the link you posted) and he was helpful too. Maybe there is a formal procedure, which would be great to read but I did it without and I'm sure if you have basic tools (I have no special mercedes tools) and a little experience you'll pull it off just fine.

Tjts1,
You're right there used diffs for sale on ebay and now that these cars are older there are ones available locally too in my area. It would be really easy to just drop in another one and cheap. The reason I did the rebuild is that I figured the used diffs would either have the same issue or develop it in a couple years. Plus I had never done a job quite like this one so I was excited to give it a try. And with cheap used ones like you mention the risk was pretty low.
 

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2008 E300 4Matic
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161 Posts
Thanks @longway and @tjts1. I am excited to try this. I don't have a closed garage. So, I will probably have to wait until the temperature is reasonable to do this job in my carport.
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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9,905 Posts
My inner used car salesman says pack the old diff with sawdust and sell the car quickly. Yes, they really used to do that...
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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9,905 Posts
PS FWIW the rear wheel bearings on the wife's CLK350 started to whine at about 75k miles. They were still whining when she drove it into a hole on a construction site (yes really - it was dark and raining) and totaled it. Before you replace the diff you could replace the wheel bearings. It won't do any harm (except to your wallet) and a heck of a lot cheaper than a new diff. Tires first though.
 
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