Are all newer F150 hubs engaged by vacume? My 04 F150 makes a loud grind noise from left hub when put in 4 wheel drive (manual Transfer case). I know its not engaging. It happens when at a stop and put in 4 wheel drive. If truck is moving it will engage. Service where I bought truck said thats how they work , you have to be moving or rock truck to lock hubs. After calling him an idiot I left without getting fixed. So do they operate by vacume when put in 4 wheel drive? Thank you in advance, Paul.

 

Yes they operate on vacuum, to disengage them. The default position on the IWEs is locked. Engine off they will be locked. Start the engine and they will disengage until you put the truck in 4x4. They should engage from 0-xxmph, although I don't want to try doing it over 55, Fords max speed for engagement or disengagement.