Whistling/Whirring sound from Tacoma

Just recently. Truck hit 100000 km and I noticed a slight whistling or wrring/humming sound coming from truck. Kind of changes pitches in sound as you feather throttle. It makes sound regardless if it is driving or standing still. Tough to describe the sound but it seems to be coming from engine compartment.

Could it be an alternator or some belt or pulley starting to wear out. Just a slight higher pitch then normal is the sound it makes.

Any thoughts?

 

You mentioned you just noticed the sound, do you think it's been doing it all along or did it just start?

 

If it makes noise while the vehicle is NOT in motion that narrows things down a lot. Likely not in the driveline, differentials, wheel bearings, carrier bearing, etc. The only things really moving at that point would be inside the engine bay.

Shoot a video/audio clip and perhaps people can help you identify it.

 

If it gets louder at idle and goes away when you floor it it might be a leaky vacuum hose.

 

get yourself a stethoscope to pinpoint. could be idler pulley, alternator, power steering.

 

Original battery?