2006 Trailblazer, XLt, V6, 4.2l 4x4.
There is a whine coming from the front of the engine. Like what the power steering pump makes when turned all of the way to right or left. But the whine happens all the time and gets louder when driving. People can hear us coming or outside the house when we pull up. Thought it was possibly a bearing or something going out in the alternator, since it is on that side of the engine. Replaced and still happening. If you want to hear the sound, listen to attached file. We are having an issue with the 4x4 and I am not sure if it is related to that, which is it wont go into 4 wheel drive. This sound happens when it is in 2 wd and all the time. No difference if AC is on or off.

 

Are you sure it's not the power steering pump? If the bearing in the pump is wearing out it could be making a whining sound at all times that would change in pitch with engine speed.

 

might even be the belt tensioner , I would remove the belt and spin everything by hand listening and feeling for a rough bearing.....not tough to do and won't take long either.

 

Thanks for your thoughts! Changed power steering pump and water pump too, but nothing changed. Figured it out to be the belt idler pulley. The bearing in it was shot. Being its right below the alternator, that is why it sounded like it was coming from there. Nice a quite now.

 

Glad you figured it out! Thanks for letting us know too!!