My 04 FX4 with 20,000 miles started making this sound (best described as like the clicking noise made when holding a ratchet by the socket and spinning it) when in 2 wd. It is coming from the right front wheel and quits when I engage 4 high. Last week dealer replaced the "four-wheel drive module" (which I assume controls the vacuum to engage/disengage the front hubs) and the hub. When I picked it up, still made the noise. Sounds to me like the hub is only partially disengaging and allowing the ends of the splines in the hub to rub. Truck is back at the dealer, service mgr. acknowledges the truck has a problem, but doesn't know what it could be-so they're looking at it again today. Salesman told me that one other customer is having same problem. Two at one dealer-someone else out there has to have come across this, if so, let me know what fixed it. Couldn't find anything using search for "4x4 noise" that matched my issue.
BTW..
Dealer is taking care of me, I'm driving a new truck off the lot during all this. Just disappointed that this problem can't be found.

Thanks

 

I had the same sound...or something close to it. It was intermittent, I couldn't replicate the noise at any specific time, it just came and went. It got worse until it was clicking all the time, then 4wd quit working altogether. I took it in, they replaced the "vacuum control solenoid" and there's been no problem since. Hope this helps.

 

Nuke,

I think my service mgr. read your reply , he called just a few minutes ago and said they were going to replace the vacuum control solenoid and would have it tomorrow. I thought thats what they replaced last week when he said the "4 wheel drive module" was replaced. Oh well, thanks for the reply-makes me think I'll get to keep my truck this time.

btw, how do you feel about the wear and tear on the hub from not being fully disengaged? I had to drive mine some while making the noise but probably no more than 100-150 miles. Did your dealer say anything about replacing the hub?

 

Nothing mentioned about the hub. Eh...it's possible things could go bad, but since I burn through so many miles as it is (20K in 6 months), it'll be soon enough when I have to start replacing parts. I've been pleasantly surprised with the quality of the truck...haven't had any other problems (other than rear diff leaking, which I have to get in for service on...) I try to avoid the dealer whenever possible, and once the warranty is done (probably by Thanksgiving?) I'll do most of the service myself. Other than that, I try not to worry about the bad things until they become bad...

 

Replaced vacuum control solenoid, test drive sounded good until I drop it into 4H and back to 2WD. Immediate noise. Service mgr and I return, pick up service tech for a ride. He says now should replace inner hub. I guess they only replaced the outer hub, which contains wheel brgs. Tech says all 4X4 hub engagement/disengagement diaphragm is in the inner hub.

Order parts, wait....

At least I'll have a completely new right front hub assy.

 

sheesh, sorry to hear that...I got mine done 10K miles ago, haven't had any problems, and I'm in and out of 4wd quite a bit. Good luck on the rest of the bits.

 

Update...
Finally fixed after 3 weeks.
Fix required inner hub and axle shaft replacement(splines had groove worn into end from incomplete hub disengagement).

 

I have a similar problem with my 05 4x4 22,000 miles. When I engage 4WDH I hear a speed-dependent clicking coming from the left front wheel. Switch back to 2WD and the noise goes away.

Does this sound like a bad vacuum control solenoid? Has this been covered under warranty for other folks?