1999 E320 4Matic Wagon 4-5 Transmission Shift Rough, Delayed
 

At 143,000 miles, the 722.6 transmission is hesitating in the uppermost gear change (4-5 or 5-overdrive?). The problem is consistent and no MIL is illuminated. Acceleration is still good, and the transmission feels strong through all the other gears with no slips or flares. At the last gear change, however, the RPMs drop down to 2000 and I feel a second more delayed clunk to around 1800 about a second later. There seems to be some subtle clunkiness when I let off the accelerator at the changing point. The fluid level seems OK at 80 C. What else should I check? Thanks!

I'm probably opening up the whole "sealed for life" debate here. But has the fluid and filter ever been changed? Mine has 143 000 km on it and was intermitantly holding in 1st gear, after a fluid (only) change, it fixed this.

Has it got the right fluid in it ?

It was changed about 40,000 miles ago...due for another according to the new 39,000 mile interval recommendation. I just wanted to be sure it wasn't going kapoot before wasting time/money changing the oil and filter.

When the fluid gets old on the 722.6 the first sign is degraded quality of gear changes - it rather "thunks" into the next gear. In my experience, 40K miles is a bit soon to be noticing such a change. Can you determine how many liters of fluid were changed 40K miles ago? If only the pan was changed (~3-4 liters) rather than a torque converter drain & full flush (8-9 liters), then I could see this as possibly a shift quality issue due to degraded fluid. But if the full change was done, I'd look elsewhere before spending the couple hundred bucks for a trans service. Take it in and have the transmission adaptation values read and analyzed by someone with the tools and knowhow. They can assess whether the transmission has faults, wear, or mechanical issues. Based on that feedback, you can make a decision on how to proceed.