Wonder if anyone can help. I have a 2lt tdi quattro Q3 under 2 years old. In the last couple of days it has developed a strange metallic grinding noise when driving along the road or reving the engine when stationary. Have done all the usual checks oil, brakes etc. Definatley here it more in side the car than out. Switched off aircon/fan so its not that. Anyone on here any idea? No warning lights coming on. Thanks