Vehicle Info:
1995 Cherokee Country
4.0 Automatic AW4 with NP231J
I honestly believe this was a DIY 4x4 conversion. VIN identifies it as 2WD. Seems to be a relatively quality install.

Hey guys, first post here. Just picked up a 95 Cherokee as an off-road only toy. Anyway, 4 hi works just fine, 2wd works great, 4 low works, but when put under a load it pops really loudly. I've read all the other threads about this and tried adjusting the linkage, replaced the transmission mount. I'm making this new thread because I have a different condition to add to mine that no one else has described.

It makes the popping sound even when sitting still. Brakes applied and wheels chocked, when I accelerate in 4 low it pops very loudly. Eventually it will pop out of 4 low altogether. I'm assuming it's something in the XFER case. Stretched chain, worn range selector, shift forks, etc?

I'm looking for anyone who has had the same or similar issue.

I know it's not U-Joints or driveshafts, etc. because it does it when nothing is turning.

Thanks in advance.

 

4LO locks all 4 together ALL THE TIME... not good for driving unless on sand or ice or snow. Most peeps only use 4 hi. I dont think it's broken. It just is not liking the road use.

 

Thanks for the reply. That's not the issue though. It's never been on pavement since I've had it. No title, no registration. Trailered to the woods and driven there.

 

Update, I pulled the T-Case apart today, the chain was pretty sloppy. Had left some wear marks inside the case. I'm thinking my problem was more related to the retaining ring that had come off of the output shaft. The shaft was able to slide in and out some. I'm hoping that was what was causing the popping. The new chain will be at the parts store tomorrow. I will post whether or not the new chain and snap ring fix the issue.

 

Yeah that's what I was thinking, chain or related because you said it happens with the brakes locked.

 

Also, the pump teeth are completely gone. Perfectly round instead of splined. Any experts on the NP231J know what happens if one runs without the pump for any length of time? I don't know how long it's been driven like that. I probably put ten miles of trail riding on it myself.

 

It sounds as though you are having an issue with a loose chain. They do stretch as they wear. If you replace it, replace the sprockets with it. The pump is necessary to get oil to the low range assembly. You might be ahead on price just to get a good case from a pick and pull

 

Final fix was a full rebuild of the T-Case. Chain was way stretched. Both Output shaft bearings had .020" radial play, Mode selector fork pads were gone and had worn into the metal. And as previously mentioned the pump teeth were gone.

Got it installed today and everything is 100% functional.

For anyone wondering, it was not hard or expensive. $150 for the full rebuild kit. And a total of maybe 5 hours to remove, disassemble, clean, replace parts, reassemble and reinstall. Some great youtube videos out there on rebuilding the NP231.

Some of the nuts holding the T-case to the transmission took some creativity. I used flex head 14mm ratcheting wrench, offset box end 14mm, and a 14mm "dog bone"

Special tools needed: blind hole puller, seal driver set, good snap ring pliers

 

Mine made that noise when the chain was worn to the point of contacting the case. The chain was jumping teeth on the sprockets. I rebuilt it pretty early when it started making that noise. Used a kit from Novak that came with a chain and name brand Japanese bearings. Cost a little more than the 150 you spent but it's my daily driver and I didn't want to go with a rock auto kit with unknown bearings in it. Did you happen to see what brand bearings came in your kit and where you got it from?