Hi guys my 05 f150 4x4 5.4l has started an odd habit. I noticed it while driving the other day and each day since but when i start it in the morning and while driving at certain speeds/rpms it gets this really loud whistle. so loud that when i use the remote start in the morning i can hear it in my closed up house 25 ft from the driveway. it usually happens around 30-35 mph and again at about 45-50 which ive noticed tends to also be around the same rpms. doesn't do it if i am accelerating hard. and only does it for about 4 seconds when i start it in the morning and the rpms go up. If i can figure out how to post a video I will try and remember to record one tomorrow morning and post it.

 

my '05 would whistle when it got cold also. It only did it at certain RPM ranges and I believe it ad some thing to do with the alternator. I never did anything about it and never had any issues other than the noise.

 

Well that makes me feel better. I bought this back in may and it's been a little quirky I think partially due to the fact it was only driven about 5000 miles a year for it's first 9 years. I've never had a vehicle make a whistle like this. I did take a video of it doing it when I was accelerating from a stop but I don't know how to load out on here

 

Passenger side exhaust manifold leak.

 

Yeah, I'm thinking hole in the exhaust

 

i definately have a leak on the passenger side. I find it odd though that this only happens around 2100 rpms and only when its under 30 degrees outside
any insight?

 

FWIW..my 04 used to do the exact same thing. Not sure what it was but my alternator went out last spring. Haven't heard any noise as of yet this winter with the new one. But it hasn't gotten real cold yet here. Oh and my exhaust leak is still there and the whistle was happening long before the leak started.
My truck only has 72K miles and was purchased new. I searched here about the whistle a few years back and from what I found then most said it was the alternator.

 

is it a high pitched whistle or more of a howl? my wife's old '04 expedition would howl randomly, i'm almost certain it was the fan clutch.

 

A semi-common issue is the alternator bearing making a high pitched whine when cold (less tan 30F deg). Mine ('06) has done that for as long as I've owned it.

 

so im sorry it took so long to get back on here. but the whistle issue has been resolved. It was the alternator. according to the mechanic its a common issue with that model year