It makes a rattling sound when there is a load on the engine but only at idling speed. Sound originates from passenger side underneath. Possibly at the back of motor. We have heard it on other silverados. Seems to be more prevalent when air conditioner is on. but doesn't seem to be associated with the air conditioner clutch. Noise does not seem to be around that area.
Sep 15, 2010 at 8:04 PM
