Wheel Hub Noise

I have an 06 F-150 STX 4x4. I have this horrible noise coming from the front driverside wheel hub. This happened after hitting a flooded portion of the road. If I put the vehicle in 4x4 it does work and there is no noise. As soon as I put it back in 2 wheel its back. I disconnected the vacuum line to the locker and the noise goes away. Has anybody had this problem before and do you think its just the vacuum operated locker? Dealer item? Do you think the axle is ruined or something totally different like a soleniod or something? Any help would be great. Thank you.