rattling from engine in lower rpms

[SevensOdd]

my engine emits a pretty loud rattle noise in the lower rpms of every gear. it sounds like its coming from the heads. but really tones down after about 3k rpm...any idea what this could be?

 

[boosted_91_tsi]

Check the crank pulley to make sure it is not separating. I had a similar noise once and it will somewhat balance itself out at higher rpm's and wont be as noticeable. The rubber tends to crack over time and the pulley will fall apart. Either way, a rattle from the engine bay... I would not drive it.