My car is making a sound which resembles two metal surfaces lightly scraping/scratching/grinding together at speed.
Typical Scenario: The car is very cold. If I rev the engine between 2k and 3k, I will hear the sound when I release the accelerator. The car doesn't have to be moving, nor in gear. Sound lasts 1-2 seconds when triggered.
The problem disappears when the engine has warmed up. It doesn't reappear until another exceptionally cold night.
The car: Golf MK5 GTi (2.0 turbo TFSI), 2006 model with 140k miles.
Any ideas what this might be? The fact it happens in neutral has thrown me completely.
Thanks for any help