I bought my wife a 2007 Ford sport trac about six months ago. It has always made a very peculiar sound and i would like to know if anyone has ever come across the same thing. It only makes this noise when you are driving about 50 mph uphill. The sound is rhythmic and coming from the rear of the truck. I would compare it to driving over sets of rumble strips but quieter. The vehicle is 4x4 and my theory is that it has something to do with this. Please let me know what you think.
Sounds like a bad bearing
Wouldn’t a bad bearing be a constant sound though?
Many people compare the sound of a bad bearing to rumble strips, just like you did
Try rotating the tires and see if that moves the sound. At least you will eliminate that from the equation.
rotating the tires would not prove anything with the bearings.
Ford has issued a TSB 07-4-5 for your vehicle that addresses a vibration that may be felt in the vehicle.
The vibration can be caused by excessive runout in the tires/wheels. So I would try swapping the rear tires/wheels to the front to see if the vibration moves with the tires/wheels.
Tester