I have a 2005 F-150 XLT 5.4L 4x4. When I was driving last week on the freeway,about 70mph, I heard a small clunk,followed by a loud grinding noise coming from my front driver side wheel. When I got home,I took the wheel off,I noticed my brake pads were worn,so, I replaced them along with new caliper pins,and brake hardware to be on the safe side. I thought maybe the caliper may have been sticking,because the little pin boots were torn,letting dirt into the caliper. Today , same thing happened. I went about 70mph, I heard a little clunk,followed by the same grinding noise. It will stay grinding until I slow down to about 5mph,in which I'll hear another clunk,then no noise. Does anyone think it might be a bearing in the hub? If it is, how hard is it to repair? How much could the bearing costif I even need one? And finally, can I do any tests to pinpoint the problem? Any help would be greatly apreciated.

 

it only does it when you are cruising down the highway?

 

The hub is losing vacuum and partially engaging, My 07 did this at around 17,000 mi. The dealer replaced the hub assembly and the vacuum solenoid that engages the auto locking hubs.

 

Check this out, sounds like it is what could be happening to you. I just changed my solenoid last week before problems arose and it took about 15 minutes. There is a lot of information on this subject on the Forum:

https://www.f150forum.com/f4/my-satu...ge-04-a-18608/

 

Mine was doing the EXACT same thing. This is a notorious problem with these trucks. It is definitely the 4x4 (partially) engaging. The 4x4 is vacuum contolled so it is losing suction. The most common reasons are a faulty solenoid, bad/rusted hub, or both. Fortunately mine was under extended warranty and I took it to a dealer to have both the solenoid and the passenger side hub replaced. Fixed the problem and it has not returned since.