Howdy all - Have a 1991 F350 XLT Lariat pickup that I keep garaged at the beach, just turned 36k on original engine. Truck is perfect....EXCEPT problem with manual locking hubs. Someone (NOT me) drove the truck, locked the hubs and drove it, but without 4WD engaged. Since unlocking the hubs, I've driven it on the road and there's an audible clicking sort of noise coming from the hub on the driver side - it increases/decreases with speed. I've removed the hub and inspected the gears and don't see anything wrong but it's still making that noise. To compound it all, I went to put it in 4WD yesterday on the beach and now cannot lock the passenger side hub - the noisy driver's side hub appears to lock just fine. I'm not a mechanic but I understand basically how a 4WD works, manual or automatic (have an '06 Rubicon at home, too). I just don't get how driving it with the hubs locked but 4WD not engaged could have done something to make one hub noisy and the other one not lock! Help!

 

Driving with the hubs in hurts NOTHING. But it does accelerate wear on the front axle u-joint.

Swap hubs and see if the noise follows. You may have have bad needle bearings inside the spindle

 

That "clicking sound" (which otherwise seems to be coming from the driver's side) MAY be that Velocity Joint up front (double cardan) --- they are typically the first to fail when drivers leave the hubs engaged for extended periods of time........the sound often appears to be originating from the driver's side wheel but in actuality is the failed Velocity Joint