Remove serp. belt and run for 30 seconds or so...see if you still hear the noise. If not, it's related to the accessories.I'm getting a noise from the belt side of the engine - I"m wondering if it might be the timing chain rubbing the cover or the block. The noise sounds like metal grinding against metal at a rhymic rate while at idle. A stethescope seems to be louder by the power steering pump. The block itself is very quiet. It didn't occur to me to listen for timing chain. Can the chain get loose enough to walk to one side of the sprocket from time to time and have the pins rub the cover or the block? The noise is louder when cold or immediately after a hard right turn. Then it fades away.
I've removed the belt and turned each pulley by hand. Bearings seem fine. There's no seep from the water pump. Idler pulley is new. Tensioner pulley has 20K. Water pump, PS and alternator are original.
Car has only 120K miles, but oil got low last interval. Would the timing chain suffer lost oiling in that instance and wear sooner?