I have read the older posts here on the super duty ford 4x4 system, but I am getting some conflicting info from a service scheduler at my local Ford dealer. I need some help guys...

Here's the situation: At 60,000 miles I noticed what sounds like a gear or bearing noise, or even a whining noise like you would hear from mud grip tires, coming from the front end area, while driving back from Kentucky to Georgia. I have quiet running street tires on this pickup.
I have a 2004 F350 crew cab XL, automatic, 4x4, limited slip axles, 430 gearing and a V10. This truck has always been extremely quiet on the highway.
This noise I described above has increased and the truck now has 70,000 miles. I have the factory 4x4 dash switch in my truck cab for the 4x4 engagement. I always thought the dash switch engaged and disengaged the transfer case, and locked or unlocked the automatic hubs. The service guy at the dealer now tells me that the dash switch only locks and unlocks the front hubs, and the front drive shaft and front differential are engaged full time. So, after checking my tires for defects, and for any play or bearing noise in my wheel bearings, I am looking at pulling the drive shaft out keep the front differential from turning, to determine if I have a bad bearing in the front axle assembly.
Now I read some of the posts here, and they say that with the dash switch in "2 wheel drive", the transfer case should be disengaged and the front drive shaft and front axle should not be turning at all.
Does anybody know for sure what is turning up front with the 4x4 disengaged on the dash switch ? I'm afraid to drive my truck out of town now and I need to isolate this issue and get it repaired. This has been a great truck and it's very reliable. I need some help on this...........

 

My interpretation has always been the transfer case engages electrically and the hubs via vacuum when you switch to 4x4. If the transfer case is always engaged, how do the hubs switch the transfer case between 4 high and 4 low? The vacuum is simply off or on. Those wires running to the transfer case must be there for something. I bet you have a hub going out.

 

Yeah, the switch on the dash engages the t-case and enables the vacuum pulse to either lock or unlock the hubs.

An easy way to check to make sure your hubs aren't stuck in the locked position is to reach behind the tires and try to turn the axle shafts at the u-joint. You should be able to turn them with ease.

 

Thankyou for the input. I thought the guy was wrong at the dealership. So, you say I need to manually turn the axle shafts by hand at the u-joints between the ends of the axle and the hubs.
Now, in what condition is the truck is ?

1. stopped, engine off, and the trans in park?
2. stopped, engine running, and in 2-wheel drive ?
3. etc

One older posts also stated that even if the dash switch is in 2 wheel drive (transfer case disengaged), that the front axle will still kinda free-turn when driving.
Im wanting to completely isolate and stop the front axle from turning at all, to see if that does eliminate my front end bearing noise. Thanks
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Yes, you can reach behind the tire and turn the axle shaft at the u-joint shown in the pic below. You can do this with the truck parked, engine off.

 

i'd say its time for a different service guy..

i agree by starting with trying to turn the shafts by hand. also try removing the lockout hubs and driving down the street; i had a hub that was on the fritz and making a similar noise/vibration.

 

Thank you for the valuable info. I will follow up and post when I get this resolved. Maybe my thread will help others as yours has helped me. Its much appreciated.......

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Thank you for the response and help with my front end noise problem on my F350 4x4. Its appreciated
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Have you figured this out yet? I have recently developed a vibration and cant seem to find it. Sounds a bit like your situation.

 

I wish I could help you at this point but me working long hours and it raining daily here in my area, has prevented me from continuing work on my truck. I drive it daily anyway. I have eliminated the front wheel bearings and the tires seem to be ok, but the noise is up front. My next move is to pull the front drive shaft which I hope will stop the front differential from turning. My front auto hubs are working ok, so removing the drive shaft should stop any further front differential movement. This should tell me if the noise is in the from axle housing or not. If I still have the noise with my front differential stopped, it could be a tire or in my 4x4 transfer box. One thing about this 2004 F350 4x4 , it is a very dependable truck. This noise started 10,000 miles ago and Ive traveled to Ohio and back to Georgia may times during that period. Of course the noise have progressively gotten louder and it has always increased and decreased with the speed of the truck on the highway. It sounds like a bearing noise up front. Similar to the noise you would experience from a set of aggressive mud grip tires.
By the way, I made a single wheel pickup out of this 2004 crew cab 4x4 dually because I couldn't find a used low mileage single rear wheel truck in my area, that was low mileage,and priced fairly.

 

have you looked at the carrier bearing in the rear driveline? i've had a "whur" develop under my truck that starts at about 10mph that is progressively getting louder, and i thinkg that's my issue.