what do you mean by that ?

I only have a 4 wheel low button in my ML320.

 

yes, that one.

the one on the upper left side of center console panel.

you will hear a thug when dis-engaging and much quiet when engaging.

 

The mechanics finally found the problem. According to their chief mechanic, [b]"the car need a new differential". It's going to take one week for the part to be shipped from Germany, and the whole day to replace it. However, they still can't guarantee that the noise will go away once they replace the differential. I will keep it updated.

 

very rare.

please keep us informed.

 

I too have this problem right now and am having to pay out of pocket for it as I am out of warranty. It is going to be massively expensive.
One of our company's salesmen has a ml430 and uses it as his travel car. Right when he reached 100,000 miles, the transmission went out. They are sealed units that can't ever be serviced. With the experience that I have had with the drivetrain, I am not too impressed even though it is a "high wear" 4-wheel drive vehicle.

 

all mercedes benz vehicles - transmissions can be serviced--- a power flush for those who do not have a torque converter drain-- with the synthetic fluid of course---i would recommend this about every 50,000 miles--- mercedes benz never recommends service on these units but some dealers do it--mine does..

 

Update

I called the dealership on friday. They are still waiting for the part to arrive from Germany.

 

Update: The dealership replaced the rear differential and wheel bearings. My mechanic called yesterday and said that the noise was still there and it looked like it was coming from the front. They are replacing the front differential today.

 

that makes sense now because it is coming from the front.

the problem is TRANSFER CASE!

 

They replaced the front differential, I picked up the car, and mechanic was really happy to tell me that the car was fixed. On my way home.....what do I hear? the same noise, only this time it's a lot quiter.