i have a 2005 f150 stx 4x4 with the small v8 with 113000 miles on it. the noise just started 2 months ago started the truck went about 4 miles it sounded like metal on metal slowed down to get off the road the noise quit. checked under the hood nothing never did it again drove on trip for 800 miles no noise. couple days later went to store about 3 miles made the noise again went to pull over noise went away. buddy said to have battery checked said sometimes low voltage could make the abs motor do weird things. the battery was bad so got new battery no more noise for about a week. then again about 3 miles from house did it again this time for longer i pumped brakes no noise difference also put in neutral and revved the motor no noise difference got ready to pull over the noise went away. any thoughts

Thanks

 

Sounds like 1 of 3 things:

1. Brake wear indicator touching rotor slightly.
2. Bad wheel bearings.
3. Bad carrier bearings or else a u-joint is on it's way out.

 

could be a 4x4 actuators or the solenoid that controls the vacum to the actuators. when the noise occurs, shift to 4x4 while its happening. if the noise stops you need to diagnos the 4x4 vacum system.