My 04 does the same thing when its cold out, below 30 degrees. Its either the alternator or one of the tensioner pulleys.

 

I remedied the squealing howling on my truck. I tracked down the problem to the idler pulley, I bought a mechanics stethescope and put the probe on all of the mounting brackets or accesories to determine the source. Unfortunately there is some noise transmitted through the belt itself. The bracket for the idler pulley had the most noise, so I removed the serpentine belt and ried spinning the pulley by hand, it didn't turn too free. I removed the bolt holding the pulley on, and the shoulder supporting the bearing was galled. My local Ford dealer had the part in stock so it only took ~1/2 hour to repair after tracking the problem down. The new pulley is plastic where the old one was steel, when I removed the old pulley the front of it was caked with dirt, so I'm assuming road grime got trapped there and allowed water to get into the bearing. Since the new pulley is plastic and a different design, I think FMC realized that it was a bad design and changed it. I probably could have got the part cheaper from someone other than the dealer, but they had the part and are only 5 minutes down the road. Now I won't have pissed off neighbors when I start my truck early on cold mornings.

 

Same here 06 5.4 xlt 10,770
-6 this morn and it really made a howl, maybe 5-6 seconds then nothing. Won't do it after it warms up...

 

had this last year on coldest of cold days. Tried a belt first, then an alternator did it. Good luck.

 

I have the same problem only on the real cold days...but I just live with it. Is it something that will get worse or is it just a noise to deal with?

 

Same thing here: 2008 SCrew, 5.4L engine, 2,000 miles.

Loud whistle upon start up in COLD weather. Has to be <25 F. After engine warms up, the whistle goes away. Whistle varies in pitch/intensity with throttle position/engine speed. I thought maybe it was a vaccuum leak from my RoushCharger; now I'm wondering about the alternator or belt tensioner.
Heard it for the first time yesterday-first in morning when heading to work, and again after work heading home. It was too cold for me to try to chase it down. Hopefully, warmer weather is on the way.
CW

 

make em change the alternator under warranty!

 

Warmer today...no whistling noted.

CL

 

I had to wait for a cold forecast, & arrange with the service manager to listen first thing in the am after having parked it at the dealer overnite...long road to China but finally they acknowledged the alternator and ended the guessing game. Luckily my dealer has free loaner cars. Good luck!

 

I need to pipe in here a little.
I think some of the comments are referring to 2 different problems. I could be wrong but some say they hear the noise at startup and then it goes away and others say it only happens during normal operation.

I have a 2005 F150 5.4 and the last 4 weeks have been pretty cold in Wisconsin. I started hearing the noise and stopped by one Ford service center and they took a look at the air cleaner. He stated some of the foam around the plastic air cleaner holder gets old and causes some kind of noise (especially if your filter is dirty). This was not the case for my truck and he agreed when he went for a ride with me.
I've noticed it most when I lock my cruise in at 59mph. It doesn't matter if I have been driving the truck for an hour it will still make the noise. At 59mph the tach is at about 1750rpm and the noise is constant. If I can hold the speed and rpm with out the cruise it will still make the noise but hard to maintain that perfect rpm. Adding throttle will make the sound go away and letting off the throttle will make the noise go away. I also hear the sound at different rpm's but easy to duplicate at 59mph and 1750rpm.

I took it to another Ford service (Capitol Ford in Madison, WI) today and their comment was that it is "normal for cold operating condition" and that it is coming from the "throttle body".
I have a big problem with the use of the word normal!

Also I mentioned reading here that it may be the alternator and they said they took the belt off and the noise continued. I'm not sure how they tested with the belt off because I couldn't duplicate the sound by sitting in park throttling to 1750rpm nor drive with break on when doing the same rpm.

This repair shop also stated that they are seeing lots of these coming in with the same problem and nothing can be done. I'm happy with the truck but not happy with the noise...and it's not like a squeak or a rattle, it is very loud, annoying, and embarrassing.
Any suggestions out there?

 

Mine whistles too!! 2008 SCab XLT 5.4L 450miles. Only had it a month and it whistles for a few minutes while warming up at all temps under 25. Its loud enough I can hear it inside the house with the doors shut. Very embarrassing. Going to tell the dealer about it next time I take it in. My previous truck ('06 XLT) only whistled a couple of times and that was in below 0 temps.

 

I agree BigMike...I'm embarrassed by the Ford power steering noise at startup also but I can shrug it off "a little" because the sound goes away once warmed up. My whistle/squeal is constant while driving down the road. I can drive for 2 hours and have the noise last the entire time and it's pretty loud inside the truck, I don't know if the people I pass hear the noise also...I hope not.

 

This is the exact same problem I had. The alternator was changed out, and I have not heard the sound again in 1000 miles. I got that same noise around 100 km/h (62 mph) and 118km/h. Also, every now and then, when accelerating keeping the engine speed constant I would get the sound, and giving it more or less throttle it would go away.

FYI, the alternator that was replaced appeared to be in new condition, as nothing was actually wore out. Maybe a bad batch of alternators? I replaced the belt at the same time. All idlers appeared free turning too.

The power steering whine has been a Ford thing for as long as I can remember. Mine makes that sound too, only lasting for about 5 seconds on a cold start, then fades out.

 

anyone ever find the TSB on this?

 

Folks try the alternator route. My problem was only while driving and not after start up. I have a slight howl at start up but all vehicles will I think when it is 0--26 like it has been here in northern MN. It took my dealer to try 2 different alternators to make it go away. Been whistle free ever since.