2009 Mercedes Benz E350 6 cyl Front Wheel Drive Automatic 13,000 miles
After driving my car for a short while it makes a very strange noise under the hood on the driver's side when it sits idle (like in the garage). It is not a fan noise, but more like a very high pitch squeal and it makes it every 20 or so seconds and will do it for hours.
The dealer has looked at it and of course could not re-create it, but it did it again just last night. The cooling fan seems to be in working order.
If I briefly re-start the car it sometimes it will go away.