Noise from front end

[bmrogers]

Mechanic friends I need your help. I have a 17 ford expedition limited 4x4. I have replaced both IWE, both front wheel hubs, both cv axles, vacuum and check valve assembly, the bearing on the driver side cv axle going into the diff. Vehicle has 168k miles on it. However when driving on the highway 55 plus I’m getting a humming noise. Put it in 4A and it will disappear briefly, place it in 4 H and it pretty much disappears until I slow down to city speed. Anyone have any idea what could be causing this problem?

 

[bmrogers]

Ive did a vacuum test and it held it. We have even done as the service bulletin suggested and locked the hubs in and it still makes the noise

 

[AWAR]

The bearings have been known to fail in the front differential. You might verify that the hubs completely disconnect and remove the front driveline as a test.