I posted the following question in another forum but got no replies. Maybe I'll have better luck here.
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I have a 2005 F150 King Ranch that I just love. The only problem I have with it is a very high pitched whine in the winter. It really sounds like some bearing going bad.

It only happens under the following conditions: it must be fairly cold -10 to +10 degrees, you must be driving (it won't happen if not under load), the RPM range is around 1800 to 2200. Outside of that RPM range its OK.

I have a friend with a 2004 F150 (smaller V8) that had the same problem. He said that when he called the dealer the rep. told him "oh yeah I have two others in right now for the same problem". They said it was one of the pulleys on the front of the engine. By a process of elimination they replaced the alternator and everyting is fine.

Does anyone have a similar issue? Any ideas why Ford hasn't addressed this issue? It is covered under standard Ford warranty or extended Ford warrany. But for the poor guy/gal this happens to after warranty they are looking at an expensive repair bill.

Anchorage, AK

 

Well if it only happens when it's cold then it's a good thing you live in Alaska where it's usually nice and warm LOL. My 97 makes a whine during real cold weather and has for years with no problems yet. I suspect it's my alternator as well. Once the engine warms up a little the whine goes away though. I don't know why yours only makes it when you are driving unless your electrical demand only then puts enough load on the alternator. If its RPM related then it should be repeatable while accelerating the engine while in park. I would say remove the belt and listen for it but since you have to drive to duplicate it that won't work as you will have no power steering. I agree that its more than likely the alternator but could also be any of the pulleys or p/s as well. Any automotive stores around you that might let you stick a reman alternator on and see if that solves the problem? Maybe someone else will jump in here with some help as well. Take care.