Perplexing whining sound only when very humid
 

I posted about a month ago trying to track down the cause of this noise http://video.google.com/videoplay?docid=-722875362697214804&hl=en
I noticed since posting that thread that the noise only comes during or in the days following a rain. Once it was dry for a few days, the noise would go away. As soon as it would rain, back it came. I have since done a transmission fluid and filter change, which solved my problem, even when it rained lightly. No metal or anything exciting in the tranny pan, btw. Until today. We have had three or four days of intermittent light to moderate showers, and the noise did not return. Today we had an absolutely torrential rain for about an hour, and I drove the car through some large puddles/creeks on the street, and back came the noise. Now its not nearly as bad as in the video, but there nonetheless. I will soon have a few weeks off from school, and would really like to dig in and figure out what is causing this noise.

Any ideas?

Check the speedo cable for a break in the plastic coating also place a finger on the glass covering the speedo and see if there is a vibration in the unit itself. I had a '78 123 which did the same thing. I pulled the unit out to repair the odo, cleaned it and the noise was gone.

this sounds like rear wheel bearings... sorry. possibly a center bearing on the drive shaft. the noise sounds too low to be in the speedo.

Interesting! Sounds like something in th drive train. Maybe the drive shaft mid/hanger bearing or whatever it's called? It would be susceptible to water. We had this go on our '85 300D, but seems to recall more of a vibration that a whine.

Graham