Hi all I am hoping for your thoughts on some noises I am hearing in 2011 2.0TDI Q5.The noise is almost like a metallic rattle , that is quite subtle and occurs for a few seconds under certain circumstances.The sound appears to be coming from the engine bay or under the engine bay uk drivers side, I have not been able to reproduce it when the car is stationary.The car accelerates fine and the gearbox feels smooth, under hard acceleration the car pulls nicely, Oil and coolant levels are fine.The noise is audible when.

1)The car engine is warmed after 15-20 minutes or so. (the noise is not audible from a cold start or for the first 20 minutes or so). 2) The car has to be moving slowly, then under quick hard acceleration the sound can be heard for a few seconds then goes.(under normal acceleration the sound is not audible)
I am not quite sure what could be causing this, and would appreciate your thoughts. Car is on 67K, had cambelt and pump change 2 years ago and gearbox fluid done at 40K.
Look forward to hearing from you.