It seems in my 05 F150 when I start the truck I get the grinding at the wheel ends while in 2 wheel drive, it lasts 20 or 30 seconds and goes away, no grinding or noise for the duration of the drive.If I shut the truck off and start it up, same thing , noise returns for 20 or 30 seconds then goes away. It's like my hubs are taking longer than usual to disengage. I have fully functional 4x4, so I'm thinking my solenoid could be on the way out even though its a year old and is the new hooded type.just wondering if this has happened to anyone else?

 

Check all your vacuum lines...could have a crack in one of the lines

 

Lines- may be brittle and/or cracked, one or both check valves might be going bad. The seals inside the IWEs could be going bad. (I went from cheapest 1st)