Comes and goes. Usually at highway speeds. If I hit the gas or let up on the gas, it goes away. I just bought the truck used with 46K miles. Sounds like it could be a wind noise from the bug deflector or the air intake(factory). My father thinks it might be a transmission noise. Any ideas? Seems to also be during the colder weather. It has been anywhere from zero to in the high 20's. I don't want to wait too long to get warmer weather because I have 60 days/3000 miles warranty.

 

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My 99 F-150 had the same noise, it was a small plastic elbow thingy that attached to the intake. They replaced it and the noise went away. My Explorer is now in the shop for the same sound! You would tink they would have figured out what the problem is by now and changed the part on al their vehicles! Don't know if it's actually the same thing on the Explorer, or on your truck being as it's newer, but that's what it sounds like to me! Sorry I can't remember what the thing was called!

 

I know the part you mean. This is my 3rd F150. The first was a 4.6, the last was a 5.4, and this is another 4.6. The first made the noise after I added a K&N. The second never made the noise...with or without the K&N...although I didn't drive it without it. I am planning on putting it on this truck as soon as the weather warms. It really only happens in cold weather when the truck is still cold. Once the truck warms up or the temp gets over 10 degrees, it stops. That's why I think it's an air intake noise also.

 

I have a 2001 W/ 5.4 that has a similar noise problem. On mine, the noise is most pronounced when coasting down from 50 to 45 and seems to go away when you accelerate. I took mine to the local Ford dealership and they said that they couldn't hear anything wrong, but when I drove home, it whistled and chirped all the way. This noise seems to be drive line related since it is only there when the truck is moving and not at idle. I'm wondering if it could be the universal joints or perhaps the pinion bearing. My truck only has 36000 miles so I wouldn't think that either of these items should need maintenance but with no grease fittings on the U-joints, I guess it's possible.

 

Some of the concerns I have just read in this thread point to a ring and pinion whine most notable between 35 and 55 mph at coast. If under power(accel or decel) the noise goes away. It could be the bearings in the rear axle, or just a "normal" rear axle whine. Mostly, if you can deal with it, it won't cause much concern. If it gets considerably worse, then have it checked out. Check with some similar trucks with similar mileage to see if yours is "out of spec".

Robbie

 

It also happens on a cold start on cold morning. As soon as I turn the key it "winds up" and then stops. Hope this helps identify the problem.

 

I have the exact same problem on my '03. Seems to be worse when its really cold. As soon as I start it, I can hear it if the temp's are really low.

Mine changes pitch as I coast and apply the brake. Almost goes away when you accelerate. If you stop at light or a stop sign, turn your wheel and you can hear it even more. Best way to describe that sound would be when a barber gets close to your ear with an electric shaver.

But the whine I hear driving is the most frustrating. The fact that it comes and goes is probably more frustrating then anything. Like I said, I think the cold has a lot to do with it. In a few months, the sound will go away. What could this be?

 

I have this noise between 43ish and 50 mph... but only when giving it gas. When I let up on it or go over 50 it goes away. I thought it could be the exaust cause it sounds like its coming from that area.

 

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