Dana 18 Go Boom

Good afternoon. So I've been having a bit of fun running around in the desert and a couple trips back and forth to work with no problems. It's been great! Then A couple days ago on the way home going about 40MPH there was a loud BANG from the transfer case and it locked up, locking the read axle up as well, so that was a fun surprise. Hopped out and looked underneath and nothing was hanging. I hopped back and started it back up. It would NOT go forward in Hi. At first it seemed seized. It would just stall the engine and wouldn't budge at all. It WOULD roll in reverse so I backed up a little then tried 1st again. Now it was popping the hi/lo shifter into neutral as soon as I let the clutch out. Low range DID work though. I had to drop to low range to get going and hobble home about 10MPH in 5 o'clock traffic with the transfer case making some... unpleasant noises.

I got home and pulled the transfer case pan off and everything actually looks ok to my untrained eye. The teeth are all there and I don't feel any unusual play in the gears. The oil was full of metal and there some pretty good sized chucks in the pan so something obviously let loose. I took a few pictures hoping someone might have an idea what it was that let go? It looks like maybe it was a washer of some sort?

 

looks like the washer that goes behind the nut on the transmission shaft, someone could have dropped it at some point.

 

I think I would have to agree but the washer was still behind the transmission gear nut. The transmission gear was loose though so maybe it got chewed up somehow behind the nut and finally failed?

 

Is the case rebuilt by you? Someone before you could be at fault. If the gear was that loose to chew the washer it would have eaten some gear too I would think.

 

No, I bought the trans and transfer case already rebuilt but that was years ago. I cleaned out all the old oil and metal chunks I could find and everything seems to spin freely. The transmission gear doesn't looked chowdered up at all. I'm planning on putting it back together this evening and see if it will go around the block without issue. Here's hoping...

 

It looks like it could be the thrust washer for the high range output gear. This is the helical cut one by the front output housing in your pic. Grab and see if it moves back and forth. A little, .015"-.020" or so is fairly normal. If it moves 1/8" on the shaft then that is the problem.