Might not be the Torque Converter
This bulletin applies to 2011 Mercedes-Benz C300 vehicles. The customer may complain about a humming, droning, shuddering, jolting or slip.
Initially, the technician might suspect the torque converter. The cause may very well involve various issues in and around the drivetrain, such as the transmission and engine mounts, propeller shafts, side shafts, front axle transmission, etc. Optimize torque converters have been installed in NAG2 transmissions after 11/2007.
Replacement of the torque converter is not effective in the case of the above-mentioned symptoms. Perform the following checks before removing/replacing the torque converter:
- Limit the transmission to first gear and determine if the complaint is still present.
- Check the propeller shaft for excessive resistance and work through procedures LI35.31-P-056961 and LI22.10-P-056910 in the service manual.
- Check the wheels and swap diagonally if necessary.
- Check whether a transmission oil change was performed recently.