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Discussion Starter #1
A lot of you helped me with doing some major maintenance on my 350 4Matic a month or so ago. Car has been running great.
However, over the last couple of days I noticed an oil puddle (about penny sized) on the floor. Put a cardboard sheet underneath and stopped driving the car.
More puddles, about a penny size a day.

Crawled underneath yesterday and it looks like oil is leaking out where the front driveshaft goes in to the transfer case.

When I did the transmission fluid change, I had noticed that the TC housing was oily and grimy but didn't have the time to investigate then. Given how there's no real good way to check the 4Matic fluid level and how hard it is to fill up, I am not driving the car currently.

However, I would like to get her back on the road and not be an expensive paper weight. The car has 88K miles on it.
  1. Any suggestions on how to fix it? Can a beginner like me attempt to do this job?
 

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I might be wrong but I have been informed that after market repair kit includes:

3 x Tapered Roller Bearing 60x89,1x15 mm NP604623/NP577617 Timken
1 x Tapered Roller Bearing 53,975x82x15 NP925485/NP312842 Timken
2 x Front and Rear Transfer Case Seals 0159971246 & 0139977246 OEM

Edit: Oops sorry, those were W212, thought could be same...
 

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They could be the same, but that takes some investigation to confirm.
I would start with checking the oil level.
Possible in the past the TC was overfilled?
Also check/clean the breather tube.
 

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Discussion Starter #6
@konigstiger - thank you for the xentry instructions. I am relatively confident with pulling out the drivershafts but opening up the T-case seems daunting.
Having never done a job of this scope, is replacing the seal easy enough? Or do I just take it to a shop and have them do it?

@ezzo - I changed the oil as part of the maintenance I did maybe a month and a half ago/800 miles.

@Kajtek - There's a breather tube? On the transfer case? I followed the DIY here and followed it to the T. Basically filled it up till it started to drip from the fill plug and called it a day. I didn't think there was even the possibility of over filling the transfer case...

I'm currently not driving the car due to how little oil sits in there (0.8L when I did the drain and fill) and the fear of running it dry which will result in more maintenance costs.
 

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Are you aware of this post (https://www.benzworld.org/threads/diy-4matic-transfer-case-fluid-change.2336329/)?

If I were you, I would clean the transfer case with brake cleaner, then drive the car for a little while and then go underneath and try to trace where the oil is leaking from. It is quite possible as Kajtek1 said that you might have over filled the TC. Overfilling is possible if the car is not leveled when you are filling the new oil. The extra oil can escape from the vent tube.
 

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Discussion Starter #9
@ezzo - I will clean the area up with brake cleaner and drive it around. I doubt if it was overfilled as I had the car level on all 4 corners with jack stands.
 

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Discussion Starter #10
So based on your recommendations, I cleaned the area up good with some brake cleaner and drove the car for about 42 miles. 7 of those were in the city and the rest were all freeway speeds. After the drive, I jacked her up. It still seemingly seeps from the seal area where the front driveshaft goes into the transfer case. But the leak seems to be much smaller.

Its seeping out of the area highlighted in blue and then pools where the red circle is and then drips on to the ground.

What do you folks recommend? Keep driving and monitoring her?

 

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Discussion Starter #13
Not sure if there is a DIY thread about this, but you will need to put a new seal.
I was afraid of that. I couldn’t find a DIY around here, but then again I not be searching using the right terms.

I would assume there would the rear seal for rear driveshaft, front seal for front driveshaft. Anything else that gets replaced?

How long of a job is it at a shop if you would happen to know?
 

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Since this all happened after you had changed the TC oil, it makes me wonder, did you use MB approved oil? If not, this may well be the reason. Using the wrong type of oil can affect seal rubber and make it fail.
Judging by the WIS diagram that konigstiger attached previously, I think you need to change the seal and the coupling flange for each side, but why do you want to do the rear seal if it is not leaking?
 

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Discussion Starter #16
@konigstiger - Thank you! The parts list is definitely very helpful! Your previous post about tightening the nut on the coupling flange - seems like I need to disconnect the front driveshaft and try to get a very deep socket on to it. Any odds you would know what socket size it is and/or what torque value I should try to target?

@ezzo - I figured if the rear drive shaft was coming off and the seal on the front is leaking, might as well replace both the seals for peace of mind?
I did use the approved MB oil in the TC case. The leak seems to have been there since before I purchased the vehicle because of the greasy mess in the area. The grime was there when I did the fluids change a month and a half or so ago. Taking the car on a 700 miles road trip seems to have exacerbates the problem some. I had the car level on all 4 corners on jack stands while doing the fluid change.
 
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