New Metallic Noise In Engine Compartment

[pwsigmund]

I've suddenly developed a sort-of high pitched metallic raspy sound in the engine compartment of my 2002 Yukon 4WD (140K). I hear it while I'm driving, but also when the truck is parked and running. It's RPM sensitive: when you rev the gas pedal it immediately responds. Been too cold to do much investigation. My first thought is that the power steering pump may be going bad, but now I'm wondering about the transmission. Could a trans going bad make such a sound while idling in Park, or would you have to be moving?

 

Any suggestions on trying to isolate the problem? I'm thinking maybe my first try should remove the S-belt and rotate the power steering and water pump pulleys, looking for roughness for starters. Ideas welcome!

[jro909]

is it like a shreek? if my trucks sits in the dead cold(way below freezing) all night the pulleys shreek for a few minutes, my buddys 08 colorado does it too..the power steering generally only makes the banshee sound when turning with low fluid...i haven't heard of a trans making noise in park...my only other experience with the metalic sound is i have a friend that i ride horses with, she towed 2 horses with a half ton z71 and it made think loud pinging when it hit 4-5k rpm so idk man..all i got

[MrYin334]

could be an exhaust manifold leak. is it like a high pitch ticking that responds to rpm?