Been loving my "new to me" Expedition for a few months now...
2004, 5.4 xlt with 85,000 miles on it.
Posted a few questions before I bought it and right after. THANKS again for all that help!!
But now...I have a strange sound that I am having a terrible time trying to diagnos and am left wondering if there is anything common that might point me in the right direction at least.
Truck makes a high pitched whine or more like a whistle under certain circumstances. Never very consistent either. Seems like when it is "under load". Usually at least 50 mph, that had me thinking aerodynamics and the windsheild trim and roof rack, but sometimes slower too. Sounds like a vacuum leak and maybe under dash or firewall area. So I tried turned heat on and off when it does it, thinking heater controls, nope. Thought he vac. activated 4x4 stuff, switched in and out of 4wd while whistle happened, nope. Varying the throttle changes pitch and volume. Friend suggested serpentine belt. I put a touch of belt dressing on the belt itself, tried WD40 ing the idler hub, and listened pretty close to the ac., alt, ps, and front drive stuff. Didn't notice anything, but of course parked and at idle or close to it. Not thinking driveline or hubs, replaced drivers rear right after I got it and that was TOTALLY different from this whistle. All fluids and lubes good. Checked most basic, typical things I can think of. Still seems either wind related on outside or vacuum under dash....? ? ?
I had read about exhaust gaskets after searching for anything possibly related on here. Not thinking that, I did those on my 1998 and that was exhaust leaking sound, clatter like. This is a on again off again whistle...
Appreciate any ideas, leads, help. THANKS!!!

 

the "whistler" bandit?...ok, a lil' humor, mine did it yesterday @ dealer...which I drove to get a EGR & vac.solenoid...had replaced the DPFE a week prior...ran great...then dumped the rpms at idle...so when leaving dealer, it cranks out shrill like an air raid...the svs. advisor came over as I got out to look under the hood...he said it's yer belt...nope, replaced a week ago with the DPFE maint. plus lil' maint items....I swear it came from the w/pump shaft or the fan clutch...read up on the issue, fan clutch should spin free when cold/have resistance when warm or full spinning rpm @ operating temp....mine is 2000 5.4 V8 7700 which does not have the electric fan setup...it was 29degrees when it did it...my neighbor said his 05' V10 350 did it also...Before anything else, I'm going to keep eye on ambient & see if it repeats...I'll post any new shreiks...please post what you do/don't do to find or fix yours...thnx! & good luck

 

I had wondered about the fan clutch ...
Really sitting here at work and wife driving the truck, not sure if it is mechanical or electric, but I THINK it was belt driven.
When cold my 1998 really made some noise.
But it was a whirring LOTS of air moving sound and easy to identify.
Few minutes of running even in zero temps and a couple throttle revs usually freed that one up. I will look into though and post what if anything I find, Thank you!!!

 

It's the turbo spooling up.

 

Uncanny...my 98 5.4 w 84k seemed to do same today. At times it sounded like a siren in the distance. Or the kind of engine noise heard via an old AM radio. Thought it might even be a neighboring vehicle. I turned off radio, all HVAC etc. Tried to isolate by speed, steering, AC on off. etc. Suspect belt or tensioner, so I went and sprayed belt dressing as much as I could....not easy to get an upright aerosol can anywhere near the belt. Took it for a 10-15 mile run and only in the first block or so did I notice it. Now, Im at a loss. It was most pronounced at low RPM..1000-1200 RPM. particularly when decelerating. Now I could not find it again. Will try some more tomorrow. Maybe the dressing, or just coincidence.

 

Whenever I start to hear that loud whining noise in mine, I simply pull over and tell her to get out.

 

The turbo...I wish!

Tell her to get out... (I wish too) but she is driving it more than I am.

Hoping for warmer weather so I can dig in a little deeper.
She drove it across the state and back this weekend, ran fine, but making the noise. Going to look at the fan/clutch next I guess, I am still wondering if the auto hub 4x4 front end stuff may be culprit, like a vacuum leak? Isn't there a component up on the firewall ?? switch or something that runs off engine vac...probably not it, but I can't help but wonder.

THANKS for all the input, hope everyone gets fixes too.

 

I had an '03 that did this and now my '06 does it also. Did it start with the cold weather? Does it happen when you are accelerating? I did some searches last winter when the '03 was doing it. What I found out was that it was the air filter. Air would leak around the none ford brand filter and make the whistle noise. Try switching your air filter to a motorcraft (ford) air filter and see it that helps.

 

I will try looking at the air cleaner too.
That sounds entirely possible!
It did begin near fall.
Worsened as it got colder, the way it occurs does happen when throttle is increased but not consistent. Not directly "connected" though.
THANKS for that one too.
I will check tonight, hopefully!

 

Just wanted to tag along on this thread since mine is doing this as well. The loud 'siren' only happens for a minute or so on a cold morning, but the faint whistle goes on and off while driving still. It definitely sounds like some sort of air turbulence whether from a vacuum line or the airbox. But it's just too cold for me to dig around to find it. And has been happening for a few months now so I don't think it is really affecting the driving of the truck.

 

Maybe we can GANG UP on this $hi+ soon!!!

 

mechanic told me it was "harmonic" whine comming from the waterpump pully and extending to the fan/fan clutch. This occurs when temps hit below your rated cooling fluid. (like a 50/50 mix should be more of a 60/40 in colder climates.) Also, the clutch oil hasn't warmed up on the fan clutch & the waterpump pully is fighting the cold fluid, plus the fan is struggling in the colder air....He said if this is a constant problem, install a heater for the block & plug it in when it's gonna be cold...Not really an option here in Az....lol But I did notice since the other day, I started w/max heat & blower motor on & have not had it since...only 3 other days where it was as cold as that day...Urban legend or physics, it seems to have worked...(knock on wood)

 

???
Mine hasn't been noticable at initial start up, even in the cold. It has been right around zero here lately. Seems worse once warmed and driving down the road. 55, 60, or higher it comes on as your accelerate and work it a lil' harder. I have tried fluctuating the throttle and even dropping into nuetral trying to narrow it down, but it does not seem directly linked to rpm...??
i am going to look at fan, clutch, belt, pulleys, and air filter SOON!

 

My 2004-1/2 F-150 5.4 also does this. In that forum Almost all are saying alternator but there are some mentioning pulley's.

 

Looked at the truck real quick last night. The K and N filter element had a couple of "folds" on each side of the gaskets where the housing seperates. I had put a little adhesive to hold those in place last summer. ?? Not sure if its enough to make the noise or not??
The fan clutch was able to spin by hand. I rolled it a couple revolutions. There was some pretty heavy drag, but it kept going. I think I was going the right way...from driver's side towards passenger's. I will look at some of the other threads here, someone stated should on be 1/4 turn or so?
Truck was stone cold, hadn't been drove in a couple days AND it was less than 10 degrees.
Still looking...