I had the same exact problem you guys are describing and just changed the belt. Would have done the one for the power steering pump as well but it cost more than the main belt and looked like the wheel would have to come off. Anyway, no noise whatsoever. My mechanic friend who gave me a hand said it was self adjusting, he didn't mess with the tension at all and it was perfect but who knows.

 

As you can see from this page taken right out of the 1997 ES300 Shop Manual, the drive belt is NOT self adjusting.

 

We have the same chirping noise problem wiht our 97 ES. I think that it is coming from the alternator/AC compressor belt. It only happens in the morning when the engine is cold. I sparyed some belt dressing on the inside of the belt while the engine was running. With the first squirt of the dressing the noise went away. A couple days later it came back again. I sprayed some more and then more again. Now, it's even worse than it was before. I am afraid that the belt dressing has turned into gunk on the belt and the pulleys. So, I'm not sure if I would recommend using the belt dressing. Or, jus tmaybe I sprayed too much of it.

 

Like I mentioned from my post, you must replace the belt, period. No belt dressing will totally eliminate the problem. Go thru the belt removal/installation instructions in the pictorial Alan attached a couple posts above.

 

OK, I was able to fix the chirping noise with our 97 ES300 and the 2000 RX300. Here are the steps that I recommend to fix this problem.

1. Check the condition of the Alternator/AC belt. (See the pics posted by lexusk8 above.) Generally, the belts last for at least a few years and for 60,000 miles or more. Decide if you have to replace the belt or not.

2) If the belt seems to be in good shape then check the belt tension. Put a ruler alongside the top portion of the belt, and press firmly with your thumb on the middle of the belt. If the belt deflects more than 1/2 inch (space between the top of the belt and the edge of the ruler) then you need to tighten the belt tension.

3) Disconnect the negative battery terminal since you're working around the alternator and you don't want to short out anything accidentally with your wrench.

4) To tighten the Alt/AC belt tension, loosen the pivot bolt, loosen the adjusting lock bolt, and turn the adjusting bolt clockwise one full turn. Check the belt tension and adjust again as needed. Tighten the adjusting lock bolt but don't tighten it too much (about 13 ft-lb). Tighten the pivot bolt (41 ft-lb). Be patient as these bolts are kind of hard to get to because of the tight space between the alternator and the side wall. Try different socket and extension combinations.

5) Reconnect the negative battery terminal.

This should take care of it. Make sure that you don't overtighten the belt. It seems that this belt loosens up a bit after a while and slips hence causing the chirping noise. Sometimes even a newly installed belt starts chirping after a year or two, if it was'nt tightened correctly when it was installed. A new belt has to be installed much tighter than a used belt. I've seen this chirping issue with many ES300s and RX300s and our 97 ES300 and 2000RX are good examples.

Good luck!
LC1338

 

Well 01-08-07 more than 4 months after my initial post, I finally brought it to get it fixed at the Lexus dealer. It ended up being "found both drive belts loose" they "readjusted" the belt at no charge and the noise has gone away.