I have a 93 190E 2.6 Sportline with 240,000 miles on it. The transmission seems to shift very well, although there seems to be a slight clunk when downshifting at a stop light. My bigger issue is that I tried to change the transmission fluid last week, and after 4 quarts, each quart I put in poured out of both sides of the transmission as fast as I put it in. I have just finished replacing the pan gasket thinking it might be the problem, but I still can't get more than four quarts in it. Any ideas what the problem might be?

Thanks,
Jason

Both sides of transmission? If you took the pan off to service the transmission filter, either you forgot to put the gasket back on (no insult intended, I've made the mistake myself), the pan bolts are WAY too loose, or you've seriously over-tightened the bolts and crushed the gasket, and now it will never seal.

Find out where the fluid is coming from and you'll know what to do then. The gasket bolts only need about 6 ft/lbs or so of torque to be tight. That's 6 pounds of force exerted 12" from the center of the bolt head - not very much at all. It's VERY easy to over-tighten these fasteners.

Thanks wbrian,

Here's a new piece of information that strikes me as odd. I checked the transmission fluid this morning after having let engine idle and shifting through all gears, and it reads almost 5 inches ABOVE MAX, and I only managed to fit 4 quarts in it. Also, the dipstick does not match the description of the dipstick in the manual for the car. The manual says it will have a min and max marker only. This dipstick has a min and a max marker for both 90F and 180F. With 240,000 miles on the car, I would perhaps suspect that this is not the transmission it started with. Any help would be greatly appreciated.

Thanks,
Jason

Jason
If you did not drain the torque converter and trying to fill with the fluid amount meant for with torque converter, you would overfill. Check dipstick with another car of same model & year just to be sure.
Sujit

You overfilled (probably because you didn't drain the torque converter as well). The overflow is probably coming from the vent.