Where could this screaming whining noise be coming from under the hood of my truck?

Bob

Squirrels. Probably squirrels.

Philadelphia Eagles

I could be some woman.

thebax2006

Use a long screwdriver and hold the tip of the screwdriver to the alternator and the handle to your ear. If the noise is louder the alternator bearings are going bad.

Anonymous

Spray soapy water on the belt while the engine is running. Noise goes away, replace the belt. Noise does not go away, check the pulleys. https://www.youtube.com/watch?v=AEUe6uKxTv8

mark_poc

It could be the alternator. Get a cardboard tube and hold it to your ear and move the other end around the engine to see if you can determine with certainty where the sound is coming from. If one of the three phases in the alternator shorts out it can unbalance the alternator and cause a whining noise. Also, you can switch your car radio to the AM band and tune to a blank spot. Turn up the volume and see if you can hear that noise in the radio. It may help to turn on the headlights and heater fan to load the alternator first. Of course, if you hear the whining noise in the radio then your alternator is bad.

JJ

My van developed a weak tensioner pulley spring .......

Susie

Have you checked all you’re fluids, especially power steering fluid?

Concerned Dad

I'm not sure but it was the hooker that didn't pay me my money so I threw her under the hood of my Porsche since the engine is in the back. Heard her screaming and whining for miles until she agreed to pay me my money.