California

After a cold start, my car pulls to a stop with a dramatic "thunk" sound that actually pulls me back into my seat. I'm braking at the same time, but it is not the brakes. After the car warms up, it stops doing it.

Is this a trany problem? A trany oil problem? A balance shaft issue?

MB will partially pay for a new balance shaft (which my dealer has sworn they scoped it and says it is fine) through the end of this year, so if it is a bs issue, are these the symptoms?

Or is it a cold transmission or a problem with the trans?

Rudeney

Don't "chase ghosts" with the balance shaft issue. There are no symptoms until you get the MIL illuminated with DTCs 1200 and 1201. Even then, there are no physical or performance symptoms since the variable valve timing control system can compensate.

I suspect your symptom is a transmission issue. There are a few possibilities. The simplest is that you have the old software code that downshifts to 1st before coming to a complete stop. This is resolved by a firmware update that holds that downshift until the car has stopped. Most dealers will do this for around $150 or less. Some will do it for free if you have a good relationship and ask for it in conjunction with another service visit. The other cause could be low fluid. In that case, I'd suggest a fluid and filter change (I recommend every 40K miles).

kb24forlife24

I have the same issue. Your transmission isn't warmed up. Like Rudeney said, go to the dealer and have them reflash the TCU for ~$150 and it should fix it. When I flush my transmission fluid I'll have the dealer do the TCU reflash as well.

California

Interesting, I didn't see your guys' replies... they said I had a cracked transmission pan... but flashing the TCU sounds interesting as well.