Crazy Tranny
 

Been driving a '97 E320 for the past three years. As soon as the outside temp drops to approx 40-45 degrees, the tranny 1.) slips and 2.) will not upshift out of first. Posted initially a couple of years ago and someone said it could be some type of spring that's internal. MB dealer said, drumroll here, replace the transmission. I've done nothing because...if I shift it to "4" rather than "D" it works great. After a mile or so, I flick it over to "D" and I have no more issues until it sits and gets completely cold again. I have noticed when it's really cold that it slips in "R" also. I have no idea what's going on internally with Drive versus "4". Why would one work perfectly, and the other be a dog in the cold? Does it really need a new tranny, or is it something a little less costly? Actually went to two MB dealers, and both said replace based on nothing more than a test drive after the car sat out in the cold overnight. Two independent shops spent some time looking into the problem, but both stated MB has proprietary equipment that keeps them from really troubleshooting this electronic tranny? Any thoughts? Thanks.

Your 1997 E320 has an early/ first production problematic 722.6 transmission. I’m surprised it’s still working, if it’s the original transmission. Valve body updated, I lost count 4 or 5 times, updated K2 drum and planetary, software updates. Any fault codes.

The cause can be stuck valve, broken pressure regulator spring in the valve body, worn clutches, contaminated never change (sealed for life) fluid or filter. If no codes, I would remove the pan, if you find metal or clutch material its time you a rebuilt, clean check for a broken PR spring while your in there.

Thanks for the reply. I did have the fluid changed two years ago (when problem noted) and they did state no metal in oil. Also, no fault codes present. Problem is MB doesn't want to chekc PR spring (would rather go for new transmission). Can an independent do this, or do they need any special equipment?

Any one mechanically inclined can change or check this spring. I posted the procedure here, http://forums.mbworld.org/forums/showthread.php?t=151331 post #23