We just traded in our 15 F150 for This very issue. Multiple vacuum lines, valves, CV joints etc. We lost 4WD completely last year during the worst snow of the year. 3 rows in one week.

Anyway, this Last time we took it in because the drone never went away. It would get worse going through roundabouts. Shift hard into 4WD and in AWD put your foot into it it acted like the front end would fall apart. I asked the dealer to drop the front diff and look at fluid/gears but they didn’t. Did a TSB for some spacers or dumb thing for IWE. Noise was still there after we picked it up. Only had 48k on it.

I won’t get into electrical issue we were having on it.

 

yes both
2016 lariat

 

Have you tried just leaving it in 4A?. This is a grinding sound, like marbles in a can being shaken?

 

My left CV was replaced this last time and made no difference.
I feel fortunate that this isn't my daily driver, so I can keep taking it back, but it is concerning others have had the same issue and could not get it resolved. I'm wondering if there is some way to get someone at Ford out to the dealer to help dig further.

 

Are you still taking it in this week?

 

Not likely with the holiday. The other dealer I'm considering is high volume. The wait time to get appointments is ridiculous typically. I'll be lucky to get it in in the next 2 weeks. I might go back to the dealer that has had it if they can get a Ford rep out to look into further.

 

Gotcha, sounds like that's what needs to happen. I'm interested to know what they find. Yours wouldn't be the first to have something going on in the front diff, if that is what it turns out to be. Good luck.

 

Can it be the front diff? I wondered if that was the issue, but from what I understand, the front diff isn't moving if the truck is in 2 high. Is that not the case?

 

In the TC with 4A, in 2H, it can turn. If you go back to post #9, and watch that video, it will explain what goes on.

 

Ya, it's rotating from fluid drag, not transferring load. I still can't figure out why it makes noise moving straight or to the right, but goes away turning left.
I should pull the fill plug on the diff to see if there is any abnormal amount of metal. I asked the dealer to check, but don't trust they actually did.