On my 2001 5.4L F-150, when i pull out somehwere, i started hearing a faint whining sound from the motor, as the RPM's get higher, it get louder. kinda sound like a quieter supercharger whine...could it be a belt or what..it just started 2 days ago??

some have said that its the alternator on other forums, thats its sounds like its bearings going bad..??

 

check the posting strange whistle from 5.4l that I brought up, some good tips there.

 

i had the same problem narrowed it down to the PS pump, replaced the pump all i can hear now is the exhaust...nice.

 

I also noticed lastnight when iam slowing down, all my lights get dim for a second, then go back to normal.....

 

i also had that same problem and it was really starting to **** me off and for some reason I started messing with my dash dimmer switch and it stopped doing it! weird huh?
the best way to narrow down the whining is to use the ol' screwdriver trick....press the business end up to whatever you think could be making the noise and the other end against your ear. it amazing how audible it makes it.

 

When was the last time you changed your belt?

 

would the PS pump cause my headlights to dim when iam slowing down also??

and speaking of PS pump, when iam turning left, the PS makes a pretty good "straining" noise. so it could be it..

 

i bought the truck used, i've had it about 2 weeks, and the belts have never been changed