I have a 1994 C220 with 155k on it, automatic transmission.

I began to notice a whine that sounds like a power steering pump thats low on fluid when I am driving between 25-45MPH. After 45, I cannot tell of the sound goes away or if its getting masked. It is not a loud sound, but is noticeable.

The sound is dependent on speed, NOT RPM. The pitch gets higher as I go faster, not as the gears change.

Transmission fluid was replaced 2 years ago by a Mercedes mechanic while it was owned by the previous owner.

Any thoughts? I heard that it still could be something in the transmission since the sound goes away when its in its final gear.

Thanks, I look forward to getting involved in the forum!