Hi Stavros, a bit more info might help us assist. If you lift the bonnet/hood is it possible to pick up which area off the engine bay the noise is coming from? Is it around the pulley/belt section of the engine or somewhere else? Does the sound dissipate or disappear as the engine warms up or after it has been run one a road trip and then placed in park? Let us know and we may be able to provide some feedback. In all such cases a dealer service centre might be able to diagnose the sound.