The higher the RPM's the louder the noise. We

The fan belt is probly worn or dirty. Try cleaning the underside or the pullys in the serpintine route............or u mite hav to go back and chec work on the timing belt is all torqued to specs. Is belt tension rite

Sounds like the idler pulley. It is what keeps tension on the surpentine belt. Usually a water pump will start dripping water through a small hole in pump that opens when the bearings go bad and start to wobble. You can spray some lube on idler pulley to see if it quiets it down some thou this is not a permanent fix. It will pinpoint the problem

Odd,possibly the AC is overcharged,or a pulley(either tensioner or
PS ) is out of line. Wish I knew what kind of vehicle. Might help.

Have your water pump and power steering pump been eliminated as the possible cause of the noise?

you can buy idler tension pulley pretty reasonable.should cost over hundred dollars.auto parts stores has them wont cost as much but dealership idler tensioner will cost more.should be able to buy one at least little above $60.00

I am not a big fan of belt dressing ... especially when you are not sure if the problem is a:

1. dirty belt ... or
2. dirty pulley ... or
3. bad bearing on a pulley (idler, tension, A/C, alt, PS)

If you are at all handy I would take the serpentine belt off and check it's condition. How to change the serpinetine belt on 97 saturn sl2 do we have to change...
Which pulley got replaced? the idler (on top) or the tensioner (lower down)? Usually the idler or tensioner go first before an equipment pulley on the alt or A/C or power steering units.

the clutch and bearing assembly is failing it is a freewheeling pulley till clutch is engaged but it has bearings which can fail

Hello, The Tensioner is not too expensive to replace. You just push on the tensioner and create slack in the belt and then remove the belt. There are only a few bolts holding this part on. Replace the part and then create space for the belt by using the tooling on the Tensioner. There should be a square fitting for a socket extension or breaker bar to fit.

It is not necessary to slip the belt over the Tensioner as the last pulley. You can slip the belt over the Alternator or any top pulley on the engine. Then release the Tensioner. You may also want to replace the belt as dry belts can be noisy at times.

You might want to turn off your A/C to verify the noise is not the A/C compressor cycling. Sometimes the A/C clutch will rust and make more noise working than when rust-free. The way you describe more noise at idle and less at higher RPM, it is characteristic of how a compressor clutch will cycle when the Freon is a little low. If the compressor is turned off, then the noise should go away if the Freon is the problem.

Carefully check the condition of the belt, the tensioner, and the idler pulley. I had the same thing happen and once I knew where to look, I could see that my idler pulley bearings were bad (understatement...they were GONE!)

Your idler pulley and tensioner need to look even and straight and not leaning in or out. A sure sign of a problem is if one or the other leans in toward where the tension from the belt would be on it.

The best way to check is to buy, rent, or borrow a serpentine belt wrench to take the pressure off and then try and wiggle the tension and idler pulley. If you feel any play, replace as soon as possible. I dragged my feet and ten days after I heard the noise, my idler pulley flew apart right as I pulled into work.

Sounds like a bearing is going in one of the components - probably alternator, water pump, tensioner, or idler pulley