I have an 07 F150 s/c and a few months ago I started to have an issue where I would hear a loud clunk then this awful scraping noise that sounded like my 4x4 was trying to engage without my turning it on. The noise would stop eventually by itself or immediately upon me turning on the 4x4. I have just changed out a bad vacuum check valve and the solenoid last night but my 4x4 still doesn't work. I have checked all the fuses associated and still nothing. Anyone have ideas of what could still be wrong?

 

I would check your wheel hubs. They are called IWE (integrated wheel end) actuators. They lock and unlock your 4x4. Vacuum on no 4x4, vacuum off it engages.

 

I did, and after speaking with a Ford Tech that I used to work with, he said "if you know the vaccuum part of the system is working and your 4x4 light on the dash doesn't come on, then the problem has to be either in your 4x4 actuator motor on the side of the transfer case or the switch on the dashboard". I went home and did exactly as recommended.....took a hammer and lightly rapped on the actuator motor and my 4x4 now works.

 

A common issue when the 4x4 system is infrequently used...