93 GC major tranny problems

My neighbor bought a 93 GC with 4.0 and AW automatic trans and 247 xfer case.The rig has in excess of 250,000 miles and I have no idea of tranny repair history. The tranny started to act up in the first week after a 60 mile long freeway trip. He pulled off the freeway and shut it down at a store. When he came back out and tried to take off, it would barely move, and the engine was revving up as he attempted to. I went down to pick him up, so the truck sat for 4 or 5 hours. I was barely able to drive it up on the trailer, but was able to back it right off when we got home. I tried to drive it foreward, but it would barely move. I shut it off and turned it back on, and it took right off like nothing was wrong. I stopped to turn around, and it wouldn't move again. I finally got it back in the driveway, then it worked OK again. The next morning he was able to start it up and move it with no problem. We dropped the trans pan and found the filter pretty clogged up, but the oil wasn't burnt. We replaced the filter and added DextronIII (the stick said Dextron II or Mercon) and everything seemed fine. He took it for a 10 mile drive and ended up being brought back on the end of a hook. This time the oil was burnt and it wouldn't move. We picked up a working AW trans out of a 90 Cherokee and installed it onto the 247. Now the Jeep won't move. If I put it in any gear you can see the slightest strain on the driveshaft with the wheels off the ground. The wierd part is that when you try to put it in park it grinds like the transfer case is in neutral, but it's not. We've tried shifting the transfer case but it doesn't make a difference. I was thinking it may be the TCU so we unplugged it to see if it would work in limp mode, but no change. I'm stumped. Any ideas?

Check the splines on the output shaft of the trans. Sounds like the output shaft is turning. Or it wouldn't be grinding when trying to be put into park. And if the output shaft is moving, but the drive shafts coming out of the transfer case are not moving. SOMETHING ISN'T CONNECTED THERE!

It's possible, but I'm not sure. That the output shafts of the transmissions might have different spline counts. Other then that, this used trans you got out of a 90 Cherokee. Had it been recently running? My advice is NEVER get a junk yard used Automatic Transmission UNLESS you know for a fact it had recently been used and on the road running.

A standard trans can sit forever, no problem. An automatic, different story. In most cases an automatic transmission that has been sitting for any length of time (least close to a year or more) are NO good. They sit around for that length of time. The clutches inside of the clutch packs dry up. You go to install them. Put in new fresh fluid and BINGO, pop that baby in gear (wizzzzzzzzzz) the old clutch material peels right off. If your lucky you get a few miles on the vehicle then it happens. Some, right away. Some take a little longer (it's the glue backing).

But a standard trans (been sitting through 2 ice ages) install that puppy and good as new. Just a bunch of helix cut gears. No friction material installed with a glue backing onto a disc that has a tendancy to peel off after sitting over long periods (check trans shift linkage also).

I had the same jeep with about as many miles on it. The 93' GJC with the quadra-trac T-case in it actually has a NP249 - not a 247 (Assuming it wasn't swapped - I think the 247's weren't until they released quadra-trac II in 1999). Perhaps the 249 failed and they put in a 247. The AW4 that was in the early 93's is actually an extremely durable transmission. While it sounds like a transmission problem, you may want to rule out the T-case. Assuming it's a 249: The 249's used a viscous coupling as a limited slip mechanism for the T-case differential. It's notorious for failing in high mileage jeeps and will often cause a ratcheting sound when turning as it starts to fail. If the VC has been damaged for some length of time, it's possible that the differential might be worn and damaged, which could cause that problem. Putting it into 4 low wouldn't help as the early 249's didn't have low-lock to bypass the differential. If the T-case differential is damaged, then it might explain why it's grinding when you put it into park - if the input shaft of the T-case is spinning and has to be stopped when you put the transmission into park, that might cause the noise. If you do have an NP247, have put it into low-range lockout, and still have a problem, then I'm guessing that it's the transmission. However, to further rule out the T-case, try spinning the input shaft of the T-case while it's out of the vehicle in different 4x4 modes (in both directions) and see if anything's obviously wrong. It should spin smoothly and freely. If it's grinding or binding then you may have found the problem. Good luck either way.

Your absolutely right about the 249's and them being nortoriously known for tearing out the viscous coupling. The #1 and main reason for this failure has been determined and directly attributed to tires.

Either not having your tires rotated and balanced or going long periods in between a rotation and balance. Improper evenly distributed air preasure/unbalanced tire preasures. Or if your really (not meaning anyone here personally) a numb nuts. Driving around with odd size tires will also cause the failure.

The output shaft of the transmission must be stationary in order to engage the trans into park. And as for spinning the drive shafts in order to check the transfer case. That can be done without removing the transfer case. Jack up the vehicle, make sure all wheels are off the ground (in order for them to freely turn). Then follow directions as Traktor (http://www.automotiveforums.com/vbulletin/member.php?u=264500) so excellently noted. They won't spin as freely, but you will/should still be able to determine if there is a problem or not.