I have an 01 excursion deisel replaced wheel bearings wheel joints upper and lower ball joints. After 3 months I am ,getting a noise I thought was idler pull letting loose. I do keep hubs in locked position while driving as I heard it will only wear wheel u joints faster as a axel will always spin. Like I said I though I was losing pully that type of rattle. I then backed truck up and heard like a gear trying to engage noise. I jacked front up and took caps off hubs and moved hubs from locked to auto and wheels turn free noise went away. OK now tonight I engage hubs and put in 4x4 and worked fine then low 4x4 worked fine no noise. Then I unlock hubs to auto and disengage 4x4 back up truck to disengage and start driving and grinding noise like bad wheel bearing starts I jack front and wheels spin free and no play in wheel bearing . Can this noise come from front diff even if axels aren't turning ? or does it soundlike a Napa hub assembly that doesn't feel bad could be bad? I almost think it is bearing in front diff how hard is it to replace diff bearings.. Any help or ideas would be greatly aprecieated could it be bad locking hub assembly making this noise. This is awesome place for advice I just hope someone has ideas.

 

I'm no expert on the components on the 4-wheel drive, but I understand how it works. You mentioned "I do keep hubs in locked position", but I'll assume that was a typo and you omitted the word "not". The 4X4 switch activates the vacuum line to the hubs when they are in "Auto" and this locks the hubs if there are no vacuum leaks and everything is working well. The transfer case locks in electrically, with a motor I believe (somebody jump in here please). If the motor on the transfer case sticks when pulling out of 4X4, the shaft will still turn the front end - making it growl a bit. I need to look at my transfer case because it's a little stubborn after all my miles and years, you might be experiencing the same thing.

 

If your front drive shaft turns while driving with the hubs in auto and the switch in 2wd, you have one or both hubs not disengaging. In 2wd with hubs in auto, you should be able to turn the front drive shaft by hand.

 

I jacked truck up today and you were right. I swapped out hubs and now with hubs in auto and switch in 2wd drive shaft. doesn't turn. I also found with hubs locked and switch in 4wd I have found that the noise I was hearing that sounds like worn bearing is coming from inside front diff. I think I now need either a used differential assembly or try searching to see if there is a rebuild kit. The gears appear to be in good shape I Just believe the bearings inside need replacing. I'm hoping I can find info on what's involved on here. May even find a 99.5 -01 front differential unit with 3.73 gears for sale. Thanks for help.