Once the car is warmed up (idling at 800 rpm), I can hear a rattling noise from the engine bay even with the lid closed. I can hear the noise while i sit in the car as well.
It is not continuous but cyclical (many times a second) and stops the minute I rev the engine above 1000 rpm.
It seems to be coming from the hydraulic pump on the right, that is driven by the serpentine belt.
When I put my fingers on the bracket holding the pump, I can feel the vibration in tune with the noise.
Anybody had anything similar, Could it be a bad bearing on the pump.
The car has 50,000 miles. model year 2002.

 

remove the belt and turn each accessory and idler pulley by hand. That should tell you what is the problem. My car was making an awful racket and it ended up being one of the idler pulleys, which was easy to replace.

 

Hello, I am having the same problem knocking at idle when engine warms.
did you ever find a solution? thanks