I have a 2007 f150 5.4 and noticed on my passanger side front, their is a weird grinding sound when in 2 wheel drive. If I put it in 4 wheel drive it goes away.. I tried swapping actuators from the passanger side to the driver side to see if I can make the sound transfer to the driver side but made no difference. I unplugged the vacuum line and can drive fine now in 2 wheel with no issue.. What would be my issue? I have the uodated solinoid on the firewall and looked at the end of the cv axle and the teeth in the acuator and do not see any damage. Thoughts?

 

When I had that grind it was a pinched vacuum line. I'd trace the vacuum lines and look for leaks or a kink. Mine was pinched behind the intake manifold. Hope that helps.

 

I had the same problem and realized my vacuum line had a crack in it.

 

If you pull vacuum doesn't it default to 4 wd ?

 

Yes, I wonder if OP locked it into 4 wheel by pulling vacuum and noticed the sound gone and assumed it was in 2 wheel? If the grinding stopped though then I can't think of anything other than vacuum leak.