Ford Super Duty (1999-2016) :: Intermittent Grinding In Front End When Going Over Bumps / Stops When Switched Into 4wd

Long time reader and first time poster, first off the truck:

1999 F-250 super duty
130,000 miles
not lifted
stock minus warn premium manual hubs ... v-10

For the past couple of years now I have had a strange grinding noise which is coming from the front end of my truck, it sounds an awful lot like if i was driving over one of the strips on the road that is made to warn drivers they are veering off the road. It first happened a couple of years ago and I took it into les schwab to have them check everything out, of course it never made the noise for them while test driving and after a visual inspection of the front end no conclusion could be made.

After about a month it completely stopped making the noise when going over bumps and i thought that "hey maybe it fixed itself!" well it did not, about 6 months after no strange noises at all it started to happen again, and once again it stopped. Now after about 8 months of it not happening it recently started again and i am determined to figure the problem out this time, it doesnt seem to be any worse of a noise or vibration but is the same as when it first started about 2 years ago. It stops when the vehicle stops, or when i switch it into 4 wheel high on the dash.

After taking it to les shwab again a few days ago they found no problems in the front end, no wheel play or noises when making tight turns (possible signs of bad wheel bearings?) and overall everything checked out well and said that the hubs do eventually need to be replaced in these. 2 days later I took it to 4 wheel parts for an inspection, after all of 10 minutes of driving they assured me that i needed new hubs and that was the cause of the problem, after installing the new hubs (warn premium manual hubs) the problem seemed to be fixed.... 3 hours of driving after the istall and no problems! Until today when I ran over a sewer drain and sure enough the grinding came back, flipped it into 4wd with a quick flip of the switch and no more noise.

I found a few similar on this board before but with no definitive solutions..... Possibilities that I have heard of that would cause this:

-- spindle bearings
-- wheel bearings
-- auto hub hydraulics
-- stock hubs (replaced)

Again this truck is all stock minus the new hubs, taking it into shops has proven to be a giant hassle because it never seems to make the grinding noise while they drive it so they check for wheel play and tell me everything seems fine.