I have a 2000 blazer ls 4wd. Anyway i have a very annoying squeaking noise every time i start my car. It goes away when it warms ups but sometimes you hear it when i drive. It makes that sound all the time when it rains or it has rained and is wet or when it is cold. It all started 4 months ago when i change the factory alternator with a Powermaster 200amp alternator. I didn't change the belt because i just replaced it 3 or 4 months before my alternator took a ****. I bought a new belt and a new tensoner to put on but i haven't yet. I'm wondering if anyone else has had this problem and if i have purchased the right thing to fix the problem or if i need to buy something else?

 

Its sounds like your belt needs to be replaced. I had the same problem when I changed out my alternator. Changed the belt and the squeaking was gone.