OK we took it back the next day to Car Max and then they took it back to the M/C Dealer. The Mercedes Dealer put motor mounts in and did a front end alignment and re flashed trans. It still shudders. Now finally they say it is the torque converter. But since it isn't a total failure it isn't going to be replaced. The remaned M/C trans came with Plate and Torque converter. Go figure. Car Max and the Dealer have had our car four almost 4 months now in total time. I'm at my Witt's end.
This Dealer and Car Max in Dulles ,Va are incompetent. We are still fighting with them.

 

They still have the car at the Mercedes Dealer and now Car Max is giving them the go ahead to replace the torque converter. I might know something in a couple of days. It is now the 15th of January 2013. And now they are saying that the unit was a Mercedes Remaned trans and torque converter from Mercedes and not from an aftermarket rebuilder..
Go Figure

 

Update The Dealer say's it's fixed now. The Service manager told me that Mercedes does not Reman or rebuild nor use anything but new parts including transmissions. He said the trans and torque converter as well as all of the other parts are New Genuine Mercedes parts. I'll find out tonight maybe if it is really fixed this time.

 

Just picked it up. So far so good. We have put 50 miles on it so far and feels like it should. I'll hold off judgment about it until we put a few more miles on it.

 

We have put about 200 miles on the CLK to date and so far the trans seems to be fine. However our Tire pressure monitor is acting up again. It was fixed previously in a software update. Maybe when they re-flashed the ECU after replacing the torque converter it went back to a previous software update. Also the Nav unit displayed the message "Nav Temp to high"
We had that issue back in June and they replaced a processor unit with cooling fan and that seemed like it had resolved that issue.
Not sure if the new unit is bad or something else is causing it.
At least we are able to use the car for now.

 

300 miles later and while waiting in line for a car wash I placed the car in park and the parking pawl didn't engage and the car started to roll back wards. I move the shifter back to drive and the car wouldn't move it just revved up like it was in neutral. I put it back in park and it still rolled. I noticed that the shift indicator on the speedometer was saying it was in Drive and that didn't change no matter which position I moved the shifter to. I also noticed that there wasn't the usual resistance in the shifter lever. I think maybe a shift cable or the linkage let go or a pin fell out on it. I don't know if it has a cable or actual linkage from the shifter to the detent on the trans. I shut the car off and tried to restart. But it wouldn't engage the starter, I guess what ever position the detent is in wouldn't engage the neutral safety switch. I called Mercedes roadside at 845 am in the morning when this happened and the tow truck didn't arrive until 130 pm. My wife and I sat in the car almost 5 hours in nineteen degree F temps and windy. We kept hitting the seat warmers trying to keep from freezing to death. Not to mention it took 35 minutes of waiting on the phone each time just to talk to the Merc Roadside people. We finally got towed to Mercedes of Chantilly,Va and they gave us a loaner car " C300 4 matic". Now I guess we will see what the issue is this time. We will be afraid to take a trip in this car from now on.

 

i would say the shift rod fell off. theres a clip that holds the shift rod to the transmission. sounds like thats all it is. the technician who worked on the trans probably didnt install it correctly. or didnt install a new one after removing it.

 

Thats what I guessed also and just got the car back today. It was a $5.10 E Clip. The Dealer said it was worn out. They loaned us a C300 4-matic and paid for towing and the repair. It is better dealing with Chantilly Mercedes than trying to go thru Car Max warranty.