Sounds funny but take a long screwdriver (mine is an 18" xcelite) and touch the alternator, tensioner pully, etc, with the point. Put the handle end up to your ear. It works like a stethoscope to help pin point the origin of the noise.
My alternator went out after 120k and after using the method above, confirmed where the noise was coming from.

 

May have to try that too.
I have done similar to try and locate driveline noise.
Thanks

 

My 03 has done this since it was brand new. When I added the K&N FIPK it got worse. A slight modulation in throttle makes it go away whenever it occurs. Happens much more often and more loudly in the cold weather (Chicago winters). I really think it has something to do with the intake air flow.

 

update....the belt resolved mine. It had looked fine to me, but I had a friend take a look, and he showed me some cracks in the underside, and said the tensioner was at the limit. much better now. Thx as always for the helpful posts

 

i bought my 03 eb 2 months ago and had the same whistle. i installed a spectre air filter and did the gotts mod. the whistle was still there. so i took it back to the used dealership and they replaced the whole intake and egr valve. about 75% of the noise level went away, but it's still there. it happens around 1500-2100 rpm.

i read on another forum that it may be the alternator bearing or fan clutch. i guess i will inspect the belt like penzly first.

 

My 98 had the same noise and i replaced the tensioner idler and belt and so far the noise has gone away

 

I got to drive the Expedition today for the first time in a while due to our HEAVY snow storm. It does seem that the whistle/whine noise is temp. related. When it got to be mid 40s and 50s in my area, the noise was gone. Today with it being cold single digits, it whined pretty well as soon as I started it. One of these days... I will get to spend some time and check out the fan clutch, belt, idler/tensioner, and other stuff. I did look at the K&N element in the air filter, made sure the gaskets were as close to being in place as possible. Thought that it may have made a lil' difference if that was the source, but doesn't seem like it made any difference. Guessing the front drive stuff. I'll try loosening the belt so I can spin the idler, alternator, and stuff...

 

Well, I'll tell you a story. I had that whine/whistle for ages in my 04EB. I finally accepted that it would just always be there. 8 months ago I ended up replacing the u-joints on the front axle after one of them disintegrated suddenly. The whine/whistle is gone!!! The u-joints were 80 bucks a piece and took me a whole saturday but well worth it. I'm more happy that my whistle is gone than anything else!

 

It's interesting how different vehicles make different noises for the same issue. My front end sounded like a family of crickets were living under there when my front u-joints were shot.

 

Well the weather has warmed up..
I sprayed some belt dressing on the serpentine belt.
Shot a little WD40 on the idler's pivot and bearing area...
sprayed a little more towards the front bearing area of the alternator through the vents.
And towards the middle shaft of the fan clutch too.

I drove it about 15 miles last weekend and no noise, which of course is going to make it that much harder to find.


U-joints and front end are supposed to be dis-engaged while in 2WD right?
They shouldn't be rolling should they? Other than a slight amount of residual drag anyways...right?
Doesn't the diff and the hubs un hook?

Thanks!!

 

The front axle turns all the time, even in 2H. The front DS does not turn when in 2H.

Not all model years have the 2H option and since you didn't post the year of your expedition, all possibilities were thrown out there I suppose.

 

Mine is a 2004. I know that it has some sort of vaccum operated hubs and a switch on the diff. I had thought that each released...The selector switch on the dash does show 2H, A4WD, 4H, and 4L. I know that there is another "select track" auto switching option set up that I do not have. I have yet to see the A4WD kick the front end in on it's own. It seems like my 98 that had same settings would engage the front when the rears slipped. I had expected the 2004 to do the same, but sure doesn't seem like it.
Thanks again for everyone's help and info!!!

 

Well I changed the oil in my Expedition this weekend since I was just able to start hearing a VERY little amount of the infamous valvetrain tick. New oil and filtered quited down to a hardly able to hear it level.

BUT the whine squeal was pretty loud at start up. Engine would slowly climb in RPMs after first starting and the noise would gain in volume and pitch. A few seconds then engine slowed and squeal quited until going away. It was colder too. Guessing it has to be one of the bearings in a tensioner or idler... maybe.
Last week I shot wd40 into each end of the alternator and towards the centers of each idler pulley.
It was quiet for about a week, but back . Thinking I am narrowing it down slowly. Figure either alt. or one of those pulleys. Just wish there was a little more roon to get at stuff. When it gets a little more warmer I will have to see about getting the shroud out of the way. We'll see.

 

I would try the belt first. Belt dressing has a habit of working for awhile and then back to the noise. Plus the belt is easy.

 

I am figuring that once I get the belt off, I should be able to at least spin/turn each pulley and accesory by hand and see if that shows anything.
Just gotta do a little dis assembly so I can get at stuff right now. Hard to SQUEEZE between the fan, shroud, hoses, and get at the drive.
THANKS for that. I am guessing it is time for a belt regardless of anything else I come across.
THANKS!!