I was driving in the snow tonight, in 4wd in my 2001 ram 2500 Cummins. At around 25-30 mph I heard a loud clunk, and my axels locked up, spinning me out into a snow bank. I shut the truck off, and tried driving again, 2wd worked fine, but I got no traction, so I attempted 4wd again, and 500 feet later it locked up again, my front diff was smoking the first time it happened, almost as if it overheated, or fried itself, but after sitting and letting it cool down for about 15 minutes it went into 4wd and worked fine, but then after 500ft... I bought this truck 2 days ago, and I’d like to know if anyone else has had this happen, and what they had to do, wether it be an actuator, or god forbid a cooked diff.

 

So.....weird. I can only guess you might have a problem with the front ring and pinion or *maybe* carrier bearings. I'd love to get my hands on this truck and see what's happening.

Give the pinion yoke on your front diff a good shake, I'm wondering if you'll find any play. Possibly a pinion nut backed off.

 

Oh and we had a high mileage NV5600 lock up on the highway on our '02....but that was in 2wd. Still, it locked the rear wheels and sent the truck into the ditch

 

Yeah, I think it's time to pull the front cover, and see what you find......

 

If it drives fine in 2WD it's likely the pinion bearing is toast. Either too much preload or no lubrication.

 

I don't disagree but not sure the bearings alone could put up enough fight to stop the whole vehicle. BUT follow your scenario through and bearings seize = bearings break apart or spin on pinion shaft = pinion slops around = ring and pinion mesh in REALLY bad ways and that could almost surely lock the front wheels

 

Could be but the diff smoking is a dead giveaway that the bearings are seized. It's a self feeding mechanism, resistance causes heat which makes the bearing tighter which causes more resistance which in turn causes even more heat. Once cooled down the bearing spins again until the heat reaches critical levels.