Noise here: https://imgur.com/a/TE4NRZE
This site always sets speaker to off, so you need to click it on.

When I unplug the 3 wire alternator plug the noise stops. When i plug it back in, the noise starts immediately for 1/2 a second, then stops for 3 to 5 seconds before starting again.

once noise starts it does not stop.

The alternator usually starts making this noise after engine warms up for 10 to 15 minutes. Once in a while the noise starts 2 minutes after engine dead cold start. Last time I started it, it ran for 37 minutes with NO noise, then i shut her down for 2 minutes and restarted the engine, then after 45 seconds the noise started.

2 different screwdrivers touching front, mid section and rear of the alternator, with other end in my ear and I hear nothing. Same with short hose touching or just very near alt.

I cant reverse spin the Alt coupler pulley clutch\decoupler, as shown in this video. See Mine behaved like his. If this is even a proper test for a toyota. My noise does sound like The Drake alt coupler pulley clutch\decoupler here: See https://au.toyotaownersclub.com/foru...m-engine-area/ Although mine also sounds like this alt rear bearing noise here:
So, is this actually the alternator making this noise?

Separate issue:

Turning accessory pulleys/tensioner/idlers by hand with belt off and hot engine I hear no noise, see no wobble and feel no oddities. Pulling/pushing them in and out, laterally back and forth(rocking), and laterally side to side I feel some play. Some more then others. pwr steer pump moves in and out a lot. tensioner same but less and also side to side. wtr pump moves in and out, but less so and rocks back and forth. AC comp moves in all 3 directions, but not by a lot. Upper idler rocks back and forth more so. Lower idler rocks back and forth just a little. I don't know how much is acceptable/normal or if I should be concerned about some of these. The Alternator I could feel no play.

toyota 2007 2gr fe engine (comes in many toyota models and lexus too)

 

It sounds like a bad pulley in the video you posted. Have you tried using a new belt?

 

Alternator decoupler pulleys are stupid wish they would go away. If the decoupler won't rotate counter clockwise then it's bad, unfortunately for you it didn't fail and seize solid so could be the source of the noise. To replace you'll likely need a decoupler puller set.

You sure the belt is not causing the squeaking?

 

I’d like to add one more note about a potentially bad belt.

For about two years I’ve been hearing an intermittent squeal from the engine on cold starts, especially when it was muggy outside. I noticed I was able to stop the noise if I turned off the AC compressor for a few seconds, but then the issue persisted either way so I was pretty confident it was my AC clutch chirping and getting worse and worse. I even started shopping around for a new AC compressor. Then one day, I replaced all my belts when I finally replaced my timing belt and all of a sudden the squealing went away completely!

So long story short, always start with the simple stuff. It could just be an aging belt.

Here is that noise I had for reference.

 

OP: You say the alternator is making the noise, but you also said you couldn't hear anything through your screwdriver-stethoscope or hose, in your effort to pinpoint the noise. This leads me to believe it is not your alternator, as the screwdriver and hose technique is a good troubleshooting method. Look more closely at the other components, pulleys, tensioner in your belt train. To isolate belt trouble as being the issue, just replace it.

 

belt replaced a few hundred miles ago. this noise just started. removed and reinstalled belt several times.pressing on belt and pulleys with engine on dont change the noise at all.

used screwdrvr and hose on all 6 pulleys. cant locate noise this way.

 

Maybe you got a bad belt? Is it OEM, purchased from Lexus? If not, you might try one. Don't settle for OEM-like or OEM from a non-Lexus dealer as counterfeits are common when buying online.

You can spray belt dressing on the belt as a troubleshooting method only. If the noise goes away, replace the belt again. If it doesn't, it's not the belt. BTW...Other than for troubleshooting, I don't recommend using belt dressing.

 

belt purchased direct from dealer parts dept. While running, sprayed both sides of belt with water did not change the noise at all.

Frustrating that scrdrver and hose did not help at all. Its fairly loud and i can hear it easy, but not at all with scrdrver or hose. pressed scrdrver onto accessories and for idler/tensioner onto elg block nearby. Also on the center bolts which dont spin. Tried two different long scrdrvers.

If the load from the alt as i plug in it is enough to make it noise, why dont pressing on idler/tensioner or any other pulley make or change the noise?

I might just replace all three. So far i cant find a video showing how to change the tensioner on avalon or 2gr fe engine.

 

Good question! While your test procedure doesn't exclusively condemn the alt, it certainly makes it a prime suspect! While you are hearing the noise with alt plugged in, you still can't isolate it with your screwdriver-stethoscope or hose? I can understand if it wasn't due to a bad alt bearing, you not being able to hear it with the screwdriver, but then, you should definitely pick it up through the hose. I have an actual automotive stethoscope, but before I got it, I used a screwdriver like you. Either is excellent at isolating bad bearings.
I wish you luck. With the cramped access, changing out the alt and/or tensioner won't be an easy job. If your belt is a new-true-OEM belt, I don't see a need for you to replace it again.

 

idlers look easy to replace. not expensive either. tensioner well its expensive and difficult. Some ppl have just changed the tensioner pulley, but others say they tried but it didnt fit.

 

This is not the belt.
You should remove the belt and rotate all the pulleys with your hand and you will find the source of the
noise.

 

done that been there. see opening post. Three different times Ive tried this.

 

This guy here uses this pulley for the tensioner. that would be much easier then replacing entire tensioner. gates wont confirm or deny that this 36174 will do the job. they do say that the 36173 is for the two idler pulleys.

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Noise stopped.

Much wtr direct from hose (not spray bottle) on different pulley and noise stopped. After 30-60 sec noise returned. Repeated this 6 times. The last two listened to returned noise for over 10min and it never stopped or changed...until more wtr.

Unplug alt or turn on AC also stops noise. Screwdrver to ear cant find source.

Free spinning pulleys fell smooth and silent. Although most have some play.

Took car for 1st street drive since noise 1st manifested months ago. Drove for 20 min. Then noise was gone. Only time ever no noise except for 2nd time w\wtr on belt and alt\AC mentioned above.

After street drive let idle for 10 min and no noise. A few days later another 10 min idle no noise. A few weeks later noise present and louder (i have recording). After about 10 min noise volume reduced and was like all previous times. Then after 5 min it went away. Then it returned for few seconds and went away for 10-30 sec or even a minute or few minutes then returned for few seconds. Over and over.

Few week later start no noise, drv for 20 minutes and no noise again

For months every time I ran engine it made this noise, now actually drving car seems to stop it.

150k miles. Belt chnged w\oem about 6 months before.

Thoughts?

 

With the noise being as transitory as you describe, it doesn't sound like something you need to concern yourself with. If it gets worse, louder, or non-stop, it will also likely become easier to isolate. You likely have slight wear or slight contamination in one of the many bearings in the accessory drive belt train, or a slight misalignment of one of the components. I had a similar noise in my Tundra belt train for years, but it went away after I tore it apart during a timing belt replacement.