LexBrett2

I keep seeing post after post about 722.9 transmission problems. I do have a simple fix to offer. It is a cheap test that only costs your time and a bit of labor. My previous car was a w230 2005 Mercedes c230 1.8L Kompressor. She developed a hard downshifting from 2nd to 1rst.

I changed the ATF oil and filter but the problem remained. My next like of reasoning was that the conductor plate was going bad. But then I had an idea, and remembered how seafoam transtune completely solved another problem that involved my power steering. Then I read hundreds of reviews on Amazon, and many suggested that the transtune could clean "sticky valves" in the valve body. I thought I would at least give it a shot before extensive repairs, nothing to lose.

So I went to Advance Auto parts one day and bough the transtune and dumped the entire 16oz. can in the ATF dipstick (i.e., obviously you cannot do that with our sealed 722.9 transmission). Almost immediately the hard shift disappeared. It completely disappeared. I had just figured out to fix the most sensitive and expensive part of my Mercedes for practically nothing. Note that before I added the 16oz. I removed 16 oz. to ensure the same fluid level. The car continued to shift flawlessly.

Now I own a w219, with 722.9 transmission and when I recently changed the ATF I pumped in the transtune. There was not a problem like my c230, but I did use the transtune and it has not caused anything bad. Just beautiful shifts from my 5.0 liter engine.

Feel free to PM if you have questions. Here is the link to my w203 transtune thread

Seafoam transtune miracle (corrected link)