Grinding from front wheel area at 20kph & above
 

Any help would be greatly appreciated. I am getting a grinding sound from the left front wheel while driving straight.. The sound stays the same when brakes are applied and does not change when selecting 4wd or 2wd.. I pulled the wheel off and had a look, but saw nothing unusual.. Any thoughts on steps to diagnose/repair the issue?
04 F-150 5.4 4x4

Thanks, that thread was great! I will post once problem solved..

Update
 

After reading the thread everything you need to know about IWE's here is what I have found out; after disconnecting the line from the intake at the check valve sound is still present whether in 4low,high or 2wd it gets a little quieter when turning right. I found that the vac line coming from the left IWE is broken.. I will get on replacing that as soon as I can.. my concern now is since disconnecting the vacuum from the intake to the check valve made no difference :( I was hoping to make it drivable until I could replace the vac line.. anyway since it made no difference does this likely mean there are more issues other than the broken vac line... I am moving next week so I desperately need to make this truck drivable.. Help!!

Might be a wheel bearing gone bad.

bearing
 

Maybe I do have 2 separate issues, bearing and vacuum line.. Is it difficult to change the bearing? or does it come as a bolt on hub assy?

I may be wrong, but I was under the impression that the front hubs need vacuum to keep them from engaging. Disconnecting would not help. The leak needs to be fixed.