Can't find source of Whine

[JEltonJ]

1st Gen 2001 Expedition has developed what sounds like Tire noise at high speeds over 60 mph. It almost sounds like tread whine from a tire made for all terrain vehicles but higher pitched. I've changed tire treads, I've changed differential fluid. Still there. Any ideas?

 

[TJs98GT]

It could be some type of driveline bearing

 

[BIG GREEN FORD]

When you go at the speed you hear the noise put it in neutral and see if the noiseis still there.
Is it 4wheel drive?
Have you checked your hub bearings?
Have you Check your drive shafts for play?

 

[JEltonJ]

The Expedition is a 2wd XLT 5.4L. The sound has been there for a couple years now and just drives me crazy while on the interstate. the high pitch still sounds like tire tread noise, but i've changed tires, flushed the rear differential. my next check is the rear wheel bearings on the driver side. can these bearings make a noise like tire tread noise? No issues other than the noise.

 

[IMINYOURCHAIR]

I have seen bearings make an assortment of noises. it wouldn't hurt to check all the bearings while you are at it.

 

[98EXPnSRQ]

Is it a constant noise proportional to speed or can you make it vary by stepping on and off the throttle?

 

[JEltonJ]

When I let up off the gas or put the transmission in N the sound frequency drops. I have sat in the back seat to listen while someones drives and it is coming from the rear of the Expedition. After coasting to 55 mph the sound goes away.

 

[98EXPnSRQ]

I would say it is the pinion gear or pinion bearing. If the noise varies when you apply and release load, this points to the pinion area. You have a lot of miles on it.