This is a 2005 Ford Excursion, 4WD, with the 5.4L V8. 4WD was thumping when engaged, and based on it hanging up when wheels were turned rather than with wheels straight, I surmised it was a defective front driver side u-joint. I did have to drive with the thumping for a few miles before I could get to a place where I could pop out the auto locking hubs, as even when set to free there were not disengaging. I replaced the u-joint (which was indeed frozen), and got new manual locking hubs, and was expecting a happy test drive but found that the 4WD is still hanging up, though perhaps not quite as bad, but hangs up whether wheels are straight or turned (which is different from before I replaced the front driver u-joint). If it is another bad u-joint somewhere I can replace that, but my fear is it is something in the differential and that's going to be too expensive and/or beyond my abilities. Before I just accept it is now a 2WD truck, does anyone have any suggestion on how to diagnose or analysis of the attached videos? The videos are with the front wheels jacked off the ground, wheel hubs locked but transfer case set for 2WD, and I'm manually spinning the tire. I filmed that same scenario with the wheels straight, then turned all the to the left, then turned all the way to the right (filenames denote wheel direction). Thanks for any help.. I've benefitted from the content on this forum quite a bit over the years.

-Jim

 

That front u-joint in the drive shaft looks crusty. I just replaced that u-joint as the 2 bearings which have the u-bolt holding them to the yoke were completely dry. Once I got into it I found the cardan joint on the other end at the transfer case was needing to be rebuilt. I would check that and see what you find. That was not a job I wish on anyone and if yours needs attention there are 2 different styles. My truck sat for awhile waiting on the right parts as I of course ordered the wrong one...not a big deal as I really don't drive it much...

Not sure what you mean by thumping, but if it's making a noise, it could be that cardan joint...

 

Thank you for the response. I'll have a look at how much of a job that would be. By thumping I mean a "soft clunk" I guess... sounds like pressure builds then releases, builds then releases, at each half turn of the driveshaft (but I can't tell if the pressure is in the driveshaft or differential or axle joints).

-Jim