My wife was complaining about a whirring sound on her Grand Prix with the 3.8. I popped the hood, listened, and could tell it was coming from the alternator area. Having replaced more than one over the years on my other GM's, I thought, here we go again.

No big deal, replaced the alternator on this 112k car. Started up the car and......................still the same whirring sound. :banghead:

So, I've apparently replaced an alternator that didn't need replacing (though I've convinced myself at 112k miles, it was about to fail anyway, so therefore, money well spent). Any ideas on what to check next? I've got a feeling that the alternative problems are more expensive then the alternator. The serpentine belt is relatively new by the way.

Bob

Take the belt off and start the car (just for a few seconds). Is the noise still there? If no, its a belt driven accessory. Check all the pulleys for lateral free-play and spin to see if any feel gritty. Replace anything that doesn't spin nice and smooth and your noise should go away. Also check power steering fluid level (not an easy task as the pump is buried in the back on the bottom under the alternator). If taking the belt off doesn't eliminate the noise, check for a vacuum leak around the PCV valve/MAP sensor area.

could it be the power steering pump, those make that noise too.