Hello I have a 2007 Expedition with the 5.4L EFI with 97K miles on it. I am hearing a whining noise almost like a blower or a gear drive sound. It does it all the time. At an idle if I step on the gas it gets faster...going down the road it i can hear it and if I put it in neutral it still makes the noise and goes up and down as I rev it. I do not think it is any thing with the transmision. Could it be one of the pulleys bearings going bad? I was thinking of replacing the Serpentine Belt as it is the orginal and take a look at them. Am I on the right track and is this an easy thing to do?

 

Pull the belt and start it up - if the whine stops it's one of the driven pulleys - most likely the alternator. If your battery is on its last legs the alternator will whine trying to keep it charged.