whirring/squealing noise!
 

I have replaced the tensioner, idler pulley, and alternator. I have a new belt on it, but I am going to exchange that one for a new one. The noise doesn't start right away when I start it in the morning. It takes a few seconds and then it kicks in. I took off the old idler pulley and there was some scraping in the middle, I thought that was my problem, so I bought a new one. I was so happy when I put everything back together and there was no sound. It took about 15 seconds, then I heard a chirp. I was like "NOOOOOOOOOOOOO!". Well, now the sound is pretty fierce sounding. Like I said, I start the blazer and it takes about a few seconds for the noise to start. Then the noise goes away after about 10 minutes of driving. After the noise goes away, it's silent. There is nothing. It's baffling me as to what it could be. I used a long handled scewdriver to check the pulleys on the alternator, the idler, and the ac, but didn't hear anything. Oh, if I take off the fan belt and put it back on, usually there is little or no noise the first time I start it. Then the second time, it starts making the noise. That is whyh ia m going to put in a new fan belt and see what that does. A couple of weeks ago I snapped the tensioner bolt off in the alternator bracket and had to have it drilled out. Since thent he tensioner bolt has not been able to tighten all the way, like it is stripped a little. I am on my way to the junkyard to get another alternator bracket and tensioner bolt since my old one has gone missing. I have a tensioner bolt in there right now, but it's the one I bought at carquest that I am going to return. I need to take that out befor eI can return it. I am going to use that money to get another fan belt. I don't want to get another belt from advance auto parts. And also, the noise doesn't get worse or better when I turn on the air conditioning.

The belt would be the first thing I'd change.
Then I would take a look at the water pump/fan pulley

What about the tensioner pulley itself?

The tensioner and pulley are in one peice. Well, I went ot the junkyard to get another alternator bracket o replace the one I have from when I snapped the bolt off. It turns out when I had the bolt drilled out, the guy who did it for me drilled a larger hole and rethreaded it. Anyway, I put the new bracket in and everything back to where it was. I went to CarQuest and returned the other tensioner I bought for the belt. I brought the belt home and realized it was the wrong size. I went to bring it back to get the right size and they were closed. My did is going to return it for me while I am working tomorrow. Anywho, I had to put the other belt back on until I can get the right belt from CarQuest. I put the belt on and started the blazer. To my amazement, there was no noise. After about 15-20 seconds, I heard a chirp. Then another chirp, then another. I turned on the ac and cranked it, and the chirping got more intense and when I gave it gas, it chirped like mad. So, I think it's the ac pulley. How much is it to replace the ac pulley and is it hard to do. It doesn't look to hard. My ac blows out freezing air, so the compressor is good. The belt I bought from Advance Auto Parts has some white on it that looks like it's wore away a little. I am giong to get the belt from CarQuest for the heck of it cause the belt I have (which is the wrong size) looks better constructed and is a little thicker.

You should be able to replace the A/C pulley without cracking the system open but it usually takes a pulley (after removing C clip) to get the thing off. A friend of mine had a similiar problem when he had his power steering pump replaced. It took a while for the squeeling noise to start but he would shred a new belt in about 3 to 4 weeks. It wasn't noticable just to look at it but I put a true straight edge against the face of the pulleys and the new PS pump was slightly tilted and it was just enough that the belt would get hot after running awhile and start squeeling then ever so slowly each rib on the belt would get peeled off...and of course wrap all up in the fan blades!

Well, I bought another fan belt, well, got it in an equal exchange for the tensioner from CarQuest. I just put it on about 1/2 hour ago and let it run for about 5 minutes. NO SQUEAK! so far. The true test will to see what it will do tomorrow morning. We shall see, the other one squeaked the first start up about 30 seconds into it running.

Now it's to return the other defective fan belt to Advance Auto Parts and put the money towards a K&N filter!