Whining like a bad alternator

:uhoh: I have a 2005 Envoy SLT with the 4.2 engine. I'm an old dog and used to fixing a lot of problems myself. A noise started developing in my wife's Envoy engine compartment and I wasn't sure what it was, but over time it got worse. I finally checked it and it sounded like the alternator was whining. The sound increases with acceleration. So, I had a second opinion by a mechanic. He said alternator too. I replaced it on my own, while cussing the engineers who designed the engine bay. After replacing the alternator with a new one, same noise. So I checked the power steering fluid. I hadn't checked it before because had no problems with steering and no noise when turning. The fluid was low and I filled, but no relief in the noise yet. Not sure where to go from here. Anyone got a suggestion?

Welcome to AF. Take the belt off and see if the noise goes away, that way you at least know if it is a belt driven component.

check the idler pully under the alternator.very common problem.