Differential problem 190D
 

I have a 1987 190D Turbo. It looks like the car has a bad differential. I've never had a failed diff in any car, so I'm a bit amazed. They symptom is a cyclical thrubing noise when the car is coasting. Under power, it's quiet. My first thought was a bad half shaft, and I it seemed louder on the right than the left. So I replaced the right shaft. I also took the time to pull the driveshaft, and replaced the flex disks (which were very worn) and center bearing. No improvement at all. I was contemplating changing the left half shaft, when my wife came home and told me that the car had made a really strange sound...the same thrubbing, only much louder for a few moments. I looked underneath, and discovered that there was a flood of gear oil coating the entire rear half of the car. The diff was almost a quart low (I had topped it off when I replaced the half shaft). The leak seems to be coming from an odd place...behind the rear support, about the middle of the cover. I'd have to remove the diff to see the source. It's definitely not coming from the vent. Sounds about the same to me now.

I can't imagine what I'm going to find inside the diff, and I'm not sure if it even makes sense to fix. Since it's very hard to find parts for a 190DT, what differentials are bolt up swaps? Can I use a diff from a 190E or non-turbo?

ti sounds as if there may be a fatigue flaw in the rear of the diff case. perhaps due to the power of the engine. i dont know what will interchange but i suspect that diffs from the 300e will fit. and the 190 16v. i suspect the ratio may be 265, right?

i think that is what my 124 body 300d was.

bad luck!

tom w

I quizzed my wife on the sound, she said it was a very loud clanging noise, which makes me think that something may have let go internally. Might be a crack in the case or rear cover causing the leak. I've never seen anything like this.

I have been able to find out that the diff is specific to the model, 2.65:1 ratio. There's some difference related to anti-lock brakes, I'm not sure what it is.The 190 16V had a 3.27 rear, which would be "good enuf", if I could find one, and be sure of fit.

i am sure it would fit but it will decrease your mileage by 20% or so.

tom w

If you intend to put a 16v one in, you'll need new halfshafts too, and the flange is different.

Can the flanges be swapped? Is the speedometer calibrated in the head, or at the transmission?