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Discussion Starter #1
Trying to download service manuals right now, but hopefully somebody can point me in the right direction faster.

From this picture: http://i.imgur.com/wpprX.jpg

Can somebody tell me what the circular part to the right and a little below of the alternator is? It has the 3 smaller circular bolt-head-looking things on it. It seems to be still when my car is idling, and as the accelerator is pushed it starts rotating after a bit and emits a loud squeal.

Thanks,
Marc
 

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The belt does feel pretty loose, definitely looser than the other one. I see how it can be tightened and will attempt to do so in the morning. In the meantime, why would this create such a squealing noise? Is the loose belt moving across the metal instead of holding on and turning it, and thats where the noise is coming from? Is this causing any harm or damage to it?

Thanks,
Marc
 

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The belt does feel pretty loose, definitely looser than the other one. I see how it can be tightened and will attempt to do so in the morning. In the meantime, why would this create such a squealing noise? Is the loose belt moving across the metal instead of holding on and turning it, and thats where the noise is coming from? Is this causing any harm or damage to it?

Thanks,
Marc
You have accurately described the source of the noise. Extended slippage will heat up the belt, causing a glaze layer to form on the contact surface of the belt. The glazing gets less traction than a fresh surface, which makes it slip more still. Extreme cases will see cracking, tearing or de-lamination in the belt. Replacement is needed when they get that bad. A little slippage here and there is fine though, so use your hands and eyes to judge how far gone it is. Compare to the 2nd belt as a guide.
 

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It seems to be still when my car is idling, and as the accelerator is pushed it starts rotating after a bit and emits a loud squeal.
It could be a loose belt, but also a problem with the AC clutch.

With the heater/AC fan turned off, the compressor clutch should be disengaged, and the compressor pulley that the belt rides on, should rotate freely, even at idle. The compressor pulley should be turning any time the engine is running.

The front part of the compressor pulley where the three bolts are does not turn if the compressor (AC) is not on. That's normal.

So first, make sure that the heater fan and AC are turned off, and see what happens. The belt should turn the compressor pulley at all times, and there should be no squealing.

Then turn on the AC. There should be a noticeable clunk or click from the compressor area, and the front part, with the three bolts, should turn along with the pulley, even at idle.

Check to see that the pulley itself does not stop turning (or noticeably slow down while the belt continues around it at the same speed) when the AC is turned on. If it does slow noticeably or stop, then the belt might be loose, or the compressor could be seizing. (That would be when the squealing would start.)

After the AC is turned on, if the pulley continues to turn as it did before the AC was turned on, but the front part does not turn except when the engine is revved up, then the compressor clutch isn't engaging properly. That could lead to metal-on-metal squealing. This could be due to the clutch being worn (gap between the clutch and the pulley is too large), or not enough current going to the clutch electromagnet to pull the clutch into locked engagement with the rotating pulley.
 

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