i've noticed this low tone knocking sound coming from my engine bay lately. a few friends identified it as my power steering pump but i'm not too sure on that. i thought i might have fkd a bottom end bearing but it doesn't sound too much like it.
characteristics:
only happens when it's really hot, or after a long drive
as the car cools down the sound fades away
i can only hear it on idle
it doesn't get louder as i rev
here's a crap quality short vid of it: http://youtube.com/watch?v=x8MkEz9VD9M
(the sound was a bit louder a couple minutes before i shot that vid)