I experienced the squeal a few days ago after driving through snow and slush on the way to work. Washed the truck on the way home and the squeal has been silent ever since (fingers crossed).

 

So this alternator issue....

Anyone know why it does this yet? And what alternator did you guys use the replace the whistling beast?

 

I have 10,000 miles on my 2011 F150 5.0 and have had the whistle noise from day one. Had it back to the dealer 3 times and they claim it is normal, I contacted Ford and they agree with the dealer, They basically said sorry for your luck but there is nothing we can do, The computer is not telling us there is a problem (WTF). Same symptoms; the whistle can be controlled by the gas pedal though out the shift cycle regardless of RPM. After reading this thread i plan on looking into the seals this weekend, This makes the most sense since the whistle is loudest out of the drivers side window. Thank you for all the posts, This is a great site!

 

number 9 torrington bearing in transmission. i had the same problem. should be covered by your powertrain if you still have it.