Strange sound 2009 2.7 4cl Engine Whine

Hi All,


I just purchased a used Tacoma 2wd, the engine has a bit of "whiney" sound that you hear from the moment it starts, near the front of the engine, kind of constant so it doesn't necessarily increase with acceleration. Could this be an idler pulley or alternator? I was wondering if others had this problem and how they narrowed the problem down?

 

More than likely it is a pulley or the belt itself. Remove the serpentine belt if the noise goes away then you know. There are several ways to isolate a pulley. I use a water hose section a foot or two long like a stethoscope and listen at each pulley while idling the engine. Be careful while doing this as to not get wrapped up in a moving component.

 

Great idea - I put a funnel on the end of the hose, held that up to my ear while I put the other end near various components (careful not to get the hose wrapped up). Isolated the noise to the alternator, The old alternator pulley did not rotate so smoothly by hand so I replaced that and the serpentine belt (as long as I had the older belt off), completed the work in under an hour and the noise is gone. Thanks so much for your input