It could be as simple as worn out/dry/brittle Belts. When the Belts age, and they do, and it gets cold or wet under the hood, the Belts will "squeal".
Inspect the Belts to see if they are cracked or glazed.
For a quick super fast way of stopping this noise spray some Silicone Spray Lubricant on the Belt. That should quiet her down. As a last ditch effort spray some WD-40 on it.
Again, this is a TEMPORARY FIX. Just so your Neighbors don't scream bloody murder at you!
Or you can be Low on Power Steering Fluid.
A simple, cursory safety check should find it quickly.
The Noise goes away in 5-10 minutes because the Belts get heated up and become supple again.
My new C300 Luxary model is having 'screeching metallic noise' when I turn my car. It is a brand new C300 luxary. Any ideas what is the issue? Power Steering Belt slipping? A/C Belt issue? AC compressor issue....?
Interesting it makes 3 or 4 screeching metallic load noise and after the car runs for a while (5/10 mins), then even if i do sharp turns, etc, it donot make the noise. I am afarid the deailer for sure wont do anything as i am not sure if i can reproduce the issue.
Please help....buying a 45K new MB and not having peace of mind - sucks!