I have a 98 4x4 F150 that just recently started roaring fairly loud. 142,000 miles. Never had to replace a bearing on it yet. I have fairly good size tires on it but they are a year old and have never sounded like this.
Yesterday, I noticed that if you swerve hard left, the roar almost quits until the truck straightens back up. No noticable change when swerving hard right. I jacked the truck up a few weeks ago and turned both tires and could hear nothing unusual.
Sounds like a bearing? How can I tell which one it is?

 

Jack the truck up, grab the wheel at the 3 and 9 o'clock positions and shake it. If you've got play, it's probably the tie rods. Do the same thing but at the 6 and 12 position, and it's probably the ball joints. Wheel bearings can show these same symptoms though, so to test that you need to jack up the truck, take the wheel, rotor, and caliper off, and do the same tests but on the wheel hub assembly to see if you've got any play there.

It definitely sounds like a bearing, I had the same sort of symptoms a month ago, and my passenger side wheel bearing was beyond shot (you could jack up my truck, shake the tire, and it'd move a good 6" all around). Replacing the hub assembly (you can't replace just the bearings in the truck, so be prepared to fork over some cash) and my pitman arm fixed my problems (also fixed my ABS light that I had on the truck for the last year which was great).

 

I jacked the front of the truck up and have a small amount of play in the upper ball joints. I spun both wheels and can not hear much moise from either side. There may be more noise on the right front than the left.
I then jacked up the rear, chocked the front wheels and put it in drive. 40 mph on the speedometer and no unusual noise.
I drove the truck again and it definitely quiets off at 25-30 mph when you swerve sharply to the left. As soon as the trucks go straight, the roar is back. No change when you swerve to the right.
It is a loud roar that seems to be getting worse. I think I will change the right front and see what that does. Any pointers before I tackle the job. It looks fairly simple.

 

I changed the right front bearing assembly and it solved the problem.
The bearing had absolutely no play in it.
I even turned the wheel and listened with a stethoscope and could hear no noise in the bearing. Strange but the truck is quiet once again.

 

That is weird but good thing you fixed it. Also, was there no play with it off the truck? With mine on the floor and me standing on it rocking back and forth, you could definitely feel the play that was being magnified by the tires and whatnot. That is pretty strange though if it had no play at all.

 

Make sure you don't have a caliper thats sticking. I had a roaring noise that went away when I would turn. Found that the force when I turned apparently was enough to make the rotor move away from the brake pad just enough to stop the noise. Just a thought. Take care.

 

If you have a bad wheel bearing you will probably hear a growl, hum, squeal or whining noise. If you hear more of a cracking or popping, or in some cases even a growling sound, its more likely a bad CV joint and not a bearing.