You didn't mention how many miles were on the engine. I've had similar symptoms with my Camrys - one was the belt tensioner - that car had about 240k when it started ....the other time it was the alternator going bad on my current 04 camry (same 2.4) with only 124k

 

Engine has 94k.... 14 years old. The tensioner doesn't seem wobbly... When the sound stops its instant not gradual. LIke its up to battery capacity or a temperature trigger ? Headlights turned off.... ac off...radio off etc... Its a mystery ...

 

Your alternator might otherwise be working fine, but that doesn't mean the pulley bearing isn't dying. It may not be the alternator's pulley bearing, either, it could be from any of those components that are driven by the belt.

I've never used the screwdriver method, but I do use a mechanic's stethoscope. They're like $15. If you are careful and have a steady hand, you can check any of those components with it.

 

Thanks for that... I didn't get much of clue with the screwdriver method either.... I have bought a LUCAS alternator from amazon for $100 to try and get through to next spring when she wants to sell the car. I hope to pop that on Friday when all will be revealed hopefully. Her battery is still performing great (2014) so I am thinking bearings or internal electrical physical contacts .... If not then it will be a/c compressor or tensioner or steering pump..... and I will have a spare Denso alternator that works..

 

Update: Changed out the alternator for a LUCAS $100 one from Amazon. Nice unit...no core charge...13.4 volts running. Changed the belt for a Duralast from Autozone. Changed the 7 year old battery for a MaXX 750CCA from Walmart. Result ? Nada nothing.. same tinny squeak remains... Squirted WD 40 down the back of the tensioner bearing and water pump bearing (Scotty tip)...no change.. Moved the power steering left to right with the engine running.... no change... No fluids of any kind dripping... I am beaten ! but now I own a spare 14 year old DENSO alternator which is perfect lol... With the belt off I twiddled all the bearings...no roughness, no play... Come on Toyotaniks and give me clue ?

 

Change the water pump. It's a COMMON failure point on both the 2az and 2ar motor

 

It's a dilemma. Yes its either the water pump or steering pump or tensioner. Sod's law states it will be the last one of the three if I start changing them out. I can hear the skittering metallic noise as I stand in front of the open hood, but she can't hear it while driving.... so I think my tactic is to wait for a water drip at the water pump or some obvious sign from the tensioner/steering pump. The steering pump parts are really cheap on Amazon with no core charge, and I downloaded the A1 YouTube video for doing the steering pump job with the free vacuum purge instrument loan from autozone... It looks fun and I would enjoy doing it now I have the technique with the belt on and off

So it's a waiting game now....

So far I am a $100 amazon alternator into this project, and I now have a perfect spare Denso alternator on the shelf, and the new MAXX battery (form factor 27F) will be switched with my 2017SE Camry when I trade her car in....So I am proceeding with caution and a fall-back plan...

Now my TP-Link router is playing up ! No rest for the wicked...

 

If you wanna wait for the water drip it's your blown head gasket. I work for a mechanic shop specialty with Toyota. If you hear a metallic noise it's the water pump

 

Thanks for that ... Good point that it may need high pressure via a blown head gasket for the water pump to drip... which is too late. Thing is that I am not sure that it is the water pump making the metallic noise and it could be the hydraulic power steering pump or the tensioner... I was sure that it was the alternator...but it wasn't... Is there any way to confirm the noise is from the water pump before I just take another guess ?

 

Take off the belt and wiggle the pulley

 

When I changed the alternator, I took the opportunity with the belt off to wiggle all the bearings..... They were all snug but not tight and not loose, and with no wobble and no noise. That's what got my hopes up that the high pitched scratchy scrapy noise was a diode in the alternator.. I was wrong... Looking at how a power steering pump works, I see a lot of small metal spinning paddles that can get wrecked by air bubbles..... Can't see how to get a hearing device (screwdriver) onto the steering or water pumps while keeping two ears attached to my head....