wow!!! this sounds just like the problem im having after they replaced the front ball joints and the ujoints for the rear axle.im wondering if its possibly they put rear diff. fluid in the front by accident,my noise only occurs when its below 50 degrees,theyve had it for three days in the shop and they cant find anything wrong.

 

cards8086, As an old ford truck mechanic, I always find these forums interesting. Being a new Superduty owner has created a lot of spare time, as these trucks are pretty bullet proof and do not need as much work as the older units, to keep them going. Still they have their problems. I just so happen have the same problem as you and have just started hunting down the soulution. On the older units, I have heard the same noise occasionally and it was nearly always due to different sized tires. I blew out a tire once and the spare tread was just enuff taller that 4x4 engagement would start the mystery noise as you describe. On my 2000 SD Lariot 350, the road slickness, plow, speed and inclines all affect the noise. All my vitals in the front end have been inspected and seem fine. Disengage the 4x4 while moving and the noise stops, which is why I suspect some sort of transfer case/gear/tire wear conflict. When you decell, the front end kind of reverse drives the transfer case which is where I think the noise is. It is not normal and I don't know why some do and don't. I have an auto tranny, with a manual 4x4 stick. If I pull up the boot, I can really hear the the noise. I can also drive with a stethescope and probe the transfer case. Theres noise there on decell only....still looking

 

Hmmm, I think I've been here. Try removing the front shaft and see if the noise goes away. If so, I know it sounds weird, but check the double cardan at the top of the shaft for play.

 

I think I know what mine is!! When I had the diff out I remember it was way to loose. the carrier preload. I'll have to get some shims and redo it when I have time....when there's torque on it the contact changes and gets noisey. I wondered when I had it apart why it was so loose....I'll get it when I have time.

 

Thanks guys,I am trying to take it easy on the 4x4 until mechanic can open transfer case.He seems to think it is the chain inside the case .

 

99 ,don't let it go to long or you'll be putting in new gears and spyders and bearings .
basically rebuilding the front diff .

Been there done that on alot of exploders.

Rich

 

Ya I know what you are saying. I'm only using it in the snow and besides its been like that since it was new. When I had it out to do the locker it looked fine.