Hi,

I am guessing you have 2 seperate problems. Those trans can be finnicky, I have been lucky so far. You can search on "C230 transmission" and probably find quite a bit of info. As for your rattle problem, I had a very similar problem and no one else really did. It sounded to me like knocking and occurred under load as you say, which would be typical of knocking. However, no matter what gas I used it made no difference, whether regular or super duper. I had both a "primary" rattle and also a "parasitic" rattle in the cat which had a loose element on one side. You can test for that by tapping on the cats lightly with a rubber mallet.

I even tested the knock sensor which was fine. I called the dealer and they said I should run REGULAR gas in it. Yeah that's what they said. God only knows why that should make it rattle less!! Anyway one day (after a couple of years) I noticed that I didn't seem to hear it. So sadly I cannot tell you how I "fixed" it. However, changing the cat did make it a lot quieter.

Mike

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra