Great web site and forums!
Just got a 2003 explorer xlt. Live in New England. Took a trip during January's 0 to -20 below cold snap. Noticed when the tempature was well below freezing and the speed was from 45-60 mph there was a fairly loud very high pitched whistle sound coming from under the hood. Also seemed to be dependent on the engine speed as the pitch would change with the engine speed - could it be an air noise or alternator bushing? Definetly NOT a squeal like a belt. Anyone had and/or found this problem.

Now that the weather has warmed have'nt heard it lately of course!

Thanks:)[COLOR=blue][B][I][FONT=arial]

I dont know if this will help,I work for FORD as mech, and we have found that the upper intakes eat orings or are plain noisy i have replaced for same consern,another direction is timing chain guides,also found to be excessivly noisey