Priceguy

I found and fixed my problem. I discovered my Lexus, as well as many later model cars, has a clutch inside the alternator pulley. My alternator pulley/clutch had worn out and locked-up shifting the pulley off center of the alternator .015". When you looked close, you could see the pulley wobble when you spun the alternator by hand. (We measured the runout on a surface plate using a dial indicator.) This pulley runout created a vibration in the serpentine belt that had my tensioning idler bouncing like crazy resulting in the low groaning roar noise coming from the belt area. I was about to buy a new alternator for something over $350 when I called a local starter generator shop and discovered they could install a new clutch/pulley on my alternator for $75!!! Whaaat??? Yep. Crazy but true. After following the advice of trained automotive technicians and replacing the tensioning idler, both stationary idlers and the ac compressor, my problem was a $75 part most of us don't know exists. Turning the ac off reduced the load on the belt and the noise would stop. Shifting the car to drive or reverse with foot on the brake reduced rpm where the noise would amplify. Bitter sweet victory after replacing all those parts I didn't need. The good news is the nightmare is over!! My Lexus is again as quiet and smooth as ever. I hope my experience will help someone else.

jonathan13

my car rattles from a pulley when the a/c is on only, i have diagnosed the problem and you can to with a few simple steps. step one go to auto part store and buy a stethoscope for automobile if you dont have one, sure u can a use pipe but its way more accurate with this tool. step 2 and 3 remove plastic trim from hood on passenger side area were water pump and belts is and remove, grab a jack and remove the driver side tire. step 3 under the tire u find 2 or 3 10 mm bolts hiding the belt area so remove. next make sure car is secure with jack stand parking brake and just be careful.( have someone help you tell them to put the emergency break on hold the brake do not let go and put the car in D while idling and foot on break to hear the noise more clear keep in mind the ac has to be on) make sure your stethoscope does not get stuck on any belts. step 4 carefully hover your stethoscope over the idle tension-er to hear sound note you do not have to put the stethoscope on top directly just hover over, next from the bottom very carefully hover you stethoscope over the water pump pulley. you should here the sound on both but it gets much louder when closer to water pump pulley! there fore the problem is the water pump because it is shot out it may not be leaking the rotating mechanism is damaged therefore needs to be replaced. now since you are already going to go into that area i recomend to switch the tensioner pulley if you can buy one say rock auto for 15$ or nearest autostore, autozone has is for 50. any ways replace the idle pulley just bcuz your there already and water pump. you can swap out thermostat but not nessary, oh yeah and might as well change the serpentine belt you will regret it if it rips later espicially if your not doing your own work, however if your problem is just the idle tensioner you are in luck and the job is so simple
good luck to us all

so if you dont want to read my description the problem is the water pump!
from mickyanic on youtube
i used a human stethpscope but it got really dirty and they might cost a little more