This is a really easy Problem to figure out your self. IMO . it is also an Equally easy problem to fix tour self.I took my 2012 to a local Ford dealer for this issue. They claimed to have repaired it. However, it came back within 12 months of the repair. They are refusing to honor their warranty because they can't duplicate the front end grinding sound. This is the crux of my issue. The sound only seems to be there after driving the truck for extended periods at high speeds. Since I hadnt taken any long trips since the initial repair, I had no idea the problem was still there. Any suggestions on how to get the sound to duplicate so I can show the dealrship?
Figure out the problem.
Start at the IWE
Pull the hoes on the Passengers side off IWE
Pull a vacuum in the larger of the two stub on IWE
20 LBS is fine let is set for 10 min a loss of 3-4 LBS/min is acceptable.
Repeat on drivers side
If one or both Fail replace the failed part. OR tell your dealer they failed they can recreate.
If they both Passed the test
Put the hose back on both IWE.
At the brake booster pull the line that leads down the IWE off the solenoid.
Again Pull vacuum to 20 LBS
Wait 10 min. I don't know what loss can be more than 4-6? It cant be gross.
if it is gross you will need lines.
If it holds. The solenoid is likely bad.
lets say The First check both IWE were bad But you want to see if the lines are bad also? on the IWE end instead of plugging them back into the IWE. Push a Golf T in the hose instead.(each side) then pull your vacuum.