Hi guys!

My 2010 GLK350 produces a noise when driving around 25 mph and less. Usually happens when the wheel is turned left. Also, the noise appears after parked under the hot sun. So my guess is something is expanding? I have a video of it. I took it to the dealership but they couldn't reproduce the problem! This is very annoying as we couldn't identify this noise.

Trying to duplicate a condition is likely the most frustrating for the owner as well as the service writer. Are you talking about the harmonic like sound? When you hear the noise after the car has been stationary in the sun, does the sound occur when the vehicle is stationary but the engine running or does the car have to be moving? If it occurs when the car is not moving then you can eliminate drive line noise & focus on something running on the engine such as the p/s pump.

Yes, there is a sharp noise as if two metal pieces are in contact. The metal sounds resonant almost. It makes the sound at speeds under 25 mph and mostly occurs when the steering wheel is turned left.

******************************UPDATE************** ****************
Problem fixed! It was just some F*cked up rotors grinding against the pads. Thanks for all
the help!

So the question remains as to what caused the noise. Pad rubbing against the rotor sounds like the caliper was not retracting all the way & pad was out further than it should be when the brakes not applied. Possibly a caliper or master cylinder issue or do the OEM pads have a wear sensor which rubs against the rotor when the pad is down to minimum thickness? The latter would create such a noise.