I got a new project. Are there any XJ experts around here?

[kingfridayace]

Not sure if anyone is interested in this, but I'm hoping I might find some knowledgeable people here. I'm not much of a mechanic, but I'm really good at googling things and making good guesses, so wish me luck!

I didn't really need a new project, but I've been on the lookout for a really cheap XJ and I finally got one. For starters, nothing works great, but I got it home without towing so that seems like a win. Previous owner said it needs a transmission, transfer case, and the catalytic converter was stollen, but I already don't think he knew any of that for sure.

I don't think the cat was stollen because everything after the headers is missing and it was just unbolted, not cut off. And the oxygen sensor plug was neatly zip tied out of the way too. I checked codes next (after realizing it was a 95 so my code reader wouldn't do much good), and the only code was 21. That indicates a faulty oxygen sensor which makes perfect sense as there isn't one currently.

I also noticed that what the previous owner described as the transmission slipping causing him to have to shift it manually starting in 1st instead of D, seemed more like the engine bogging while accelerating. It starts strong, but then the power cuts off and the rpms drop to almost nothing. It seems to me that could be easily related to air/fuel and have to do with the fact that there's not oxygen sensor, so I'm hoping I get lucky there.

Transfer case isn't perfect, but it seems to shift into 4hi well. It will go into 4low but pops out of gear sometimes when I was testing.

My current plan is to replace the exhaust and oxygen sensor and cross my fingers. I think it's the easiest way to eliminate the CEL and help me diagnose other potential issues better. And If I get really lucky, I might even be able to get it registered and on the road so I can drive it to the shop to fix anything I can't on my own.

[Java]

Congratulations! XJs are awesome, and it looks like it's got a nice lift and tires already. :thumb: I'm not an expert but I know a little, so...

I'd guess someone sold the cats along the way, they are going for a premium now. The transmission is electric shift so you may be on to something, that would be very cool if a sensor fixed it. Hope so!! The NP231 is notorious for shift bushing / linkage issues, I bet it's just that. Replace the fluid with synthetic 10w30 and you'll be shocked at how smooth it works.

Info links:

https://www.novak-adapt.com/knowledge/aw4

https://www.novak-adapt.com/knowledge/transfer-cases/np231

https://www.amazon.com/gp/product/B008VPW5LS/ref=ewc_pr_img_1?smid=ATVPDKIKX0DER&psc=1

[kingfridayace]

Sweet! That's the kind of stuff I wouldn't have found on my own. Thanks!

When you say "Replace the fluid with synthetic 10w30" do you mean in the transfer case? I thought it got Dex/merc III like the transmission. Just based on some other forums I've been reading. I'm also going to do engine oil, transmission, and transfer case fluid just in case they haven't been done in a long time, so if you have any specific recommendations for those, I'm all ears.

[Java]

Yes, I actually use it in everything on my Jeep- engine, transmission, transfercase and axles all use Mobil1 10w30, and my Xterra is the same except the transmission uses Valvoline Maxlife. It makes carrying extra fluid easy! I don't think the AW4 would like it, but everything else would. 10w30 and 90wgear oil are the same weight but measured on different scales hence the different numbers. The synthetic is just better.

[kingfridayace]

I had no idea. I'll have to look into that, but consolidating fluids so I don't have to remember as much sounds ideal. Thanks!

[xaza]

Replace exhaust and sensor and that will eliminate what you know is wrong with it. Always start with what you know and save the guessing for when you are out of solid answers. I disagree with changing T case with 10-30. I run Dex merc, always have and last time we pulled it apart it was in great shape. Your issue with kicking out of gear in 4 low is likely a bent or misaligned shifter, typically at the t-case. Try shifting into 4 low from under truck and see if anything is binding or preventing full engaging. After shifting from below try it out and see if it stays in gear. Transmission gets a bit more difficult but hopefully is not an issue after getting engine running correctly. Drain tranny fluid into a clean (I mean very clean) drain pan (clear jar is even better). Run a magnet through the fluid and see what sticks. Big chunks or a ball of metal is bad. Replace tranny filter (requires dropping pan so have new gasket for that) and refill with Dex Merc. Add lucas to the tranny fluid. It is thick and helps to do lucas first or intermittently with tranny fluid to help it run down the tube to transmission. Do the standard checks on that thing. Raise the front tires off the ground (one at a time) and use pry bar to lift up and out on tire. Watch for movement from steering knuckle, any movement and you will need a bearing assembly. Have someone start the truck and turn the wheel back and forth. Some slower longer turns and some quicker short turns (just enough to get tires turning and cause a switch in direction of force). While this is happening watch for any movement from tie rod ends, track bar and control arms. tie rods may rotate slightly but any in and out is a bad rod end. Any movement from track bar or control arms is likely bad bushing, check to make sure bolts are tight and if they are replace bushings. You do not want to find out what speed wobbles are like..trust me on this.

[xaza]

I had no idea. I'll have to look into that, but consolidating fluids so I don't have to remember as much sounds ideal. Thanks!
You still have Dex Merc in tranny so you really aren't reducing the different fluids

[Java]

opinions vary...

https://www.novak-adapt.com/knowledge/transfer-cases/np231

"Fluid capacity of the 231 is from 1.5 up to 2 quarts. ATF is the factory recommended fluid, however many individuals have chosen to run a straight 30 weight oil or 5W30 in a mineral or synthetic. Our experiences with these and those reported to us by our customers indicate positive results in noise reduction and wear resistance."

[xaza]

Novak is a quality company that knows their stuff. That was a good read thanks.