My 420SEL has an annoying whistling sound at highway speeds of 75mph and higher. It's coming from the mirror area of the passenger door. I've tried everything to isolate the problem and try to fill whatever crack/hole is causing the noise. It's incredibly annoying. [:@] I thought it might be the molding around the door, but I think I've eliminated that as the cause. I put some petroleum jelly around the areas that I thought might be causing the issue, but I've had no luck. The sound goes away if a window is cracked or the sunroof is up.

Has anyone experienced this? If so, do you have any suggestions?

 

take a card, playing cards work good. run it along the area between the glass and the weather strip, if the card goes between the glass on weather strip there is your leak. It is probably coming from the front window. Sounds like the window to seal, as it goes away when opened, do the same thing with the rear window also, noisy sometimes done come from where you think they do. The jelly really won't seal, your better off with silicone spray. Do your windows come all thbe way up? Check this also. If you find the leak this way, get some sticky on one siding door weather stripping and put an piece were you found the gap.