Noise from Fan Housing

For the past several weeks, there has been a loud, high pitch noise when I first start my engine. It goes away as the engine warms up, or at least becomes very faint and only audible when the engine is rev'd. At first, I thought it was just the fan belt, but after checking into it, it appears to be coming from inside the fan housing. I took the fan belt off and it disappears completely. Any thoughts?
Troy http://speedster.hopto.org

Hey Troy,

Make sure the alternator strap is tight and that the alternator hasn't slipped forward or backward. The fan needs to be centered in the shroud. These motors vibrate a lot, as you know, and things loosen up rather quickly. Also check the large 36mm nut on the fan itself to make sure it is tight too.

The clamp and nut both are tight. Any other ideas?

FYI. I didn't realize that the fan is unprotected behind the shroud. I'm REALLY glad I didn't try to reach back in there with the engine running, could have easily lost a finger or two.
Troy

Look for a leaf or peace of trash in the fan itself. if not that you may have a alternator bearing fixing to go out and you can change them yourself if you have the pullers and a press.

It sounds like something's not centered correctly; that's very possible given the quality of the Oriental aftermarket parts on these cars. See if the fan fasteners on both sides are tight. I swapped all my tin for OEM German stuff; it works and fits better.

The fan itself could be bent. I had one actually break at the mounting location where the 36mm nut attaches. As I removed the 36mm, the fan cracked and broke.
With the engine off and the fan belt removed, check the trueness of the fan by spinning it by hand. Put you finger on the rim of the fan on the back side of the shroud, and rotate the alternator by hand. Check for wobbliness or if the fan spins untrue. If it doesn't spin evenly replace it with a quality balanced fan. It will save your alternator.

Push on the shroud while the engine is running.
It happened to me a couple years ago and I found that the shroud was a little loose.
Tightened up the bolts and the noise went away.
Another time I had a fan that was not true. Check for that if it isn't the shroud.

may be a bearing, causing a slight wobble, causing a slight whistle, causing a cooling fin tip to grind off, causing a fin to brake loose, causing unbalance fan to EXPLODE, causing the alternator stand to break and causing you to swear alot, this is if your lucky. Hopefully it dose not cause you to get in a accident. Check it before you wreck it!!
Cabanaboy ~ been there

Just got my car back from the shop and it turned out that there were actually two sources of noise. The loudest noise was from the fan belt, which sure surprised me. It did not appear too have too much slack in it, but apparently was too large so they replaced it with a smaller belt and that noise disappeared. The other noise was from a piece of foam rubber that apparently got sucked into the fan housing some how. Thanks for all the suggestions.
Troy