HELP!!

Alright so here's the problem and a little history to maybe help people point me in the right direction.

It's a 90 XJ 4.0L auto w/ np231.

About 2 weeks ago I was out on a trail with a freind of mine, I was on an incline when all of a sudden I lost 4x4 heard this nasty grinding sound and that was that. Luckily we weren't too far in and I got back in 2wd fine. Took it back to a friends house, figured I knew what the problem was, pulled the vacuum disco housing and the fork was snapped

Got a new fork, spaced the fork to perminantly lock the front and the 4x4 was working fine again.

Fast foward to a week later (two days ago) Me and some freinds are on this pretty nasty trail somewhere around Calibogie iirc, very steep hills and a lot of up and down, the jeep was doing fine and keeping up with my friend who was in front of me untill the very last hill. I was going up then all of a sudden I loose 4x4 again and it starts making this grinding noise, so my friend hooks onto me and pulls me up. I go to shift into 2hi and it was still making the soud..wtf..so I play with the shifter a little and find a sweet spot between 2 and 4 hi that it wasn't making the sound and limped it home. Now I have to mention too that if I'm driving the truck around town at normal speeds of say 40-50km/hr in 4hi (snow covered roads of course) it will make a slight popping sound every once in a while and I've been told that it might be the TC chain.

I'm not taking this thing back out again untill I get this figured out for sure this time becuase I've been lucky both times so far and I don't wanna push it.

Alright so that was a post from another webboard, in which no one could offer at least a little bit of help, I'm hoping you guys will be of more help. I picked up a freind last weekend and decided to demonstrate the issue (the fact that it was working fine on flat ground) as I demonstrated it worked just fine. Then as we were driving down the road (in 2wd) I heard a little thump and it started grinding again. I tried playing with the TC lever and managed to get it to stop if I pulled it up and kind of put it in between 2hi and 4hi and then even in 4hi or 4lo it would stop grinding but not actually engage 4wd in either range.

So at first I thought it could be fluid level in the front diff, so I drained it and topped it up and tried again...the grinding was still there. Next I thought it may be fluid level in the transfer case, did the same and the grinding is still there. Now the front driveshaft is spinning when it's in 4wd and it stops when it's in 2wd but the grinding is there in all ranges depending on angles I guess. I checked for slippage in the linkage and there doesn't appear to be any as you can see the rust all over the linkage and there's no spots that have worn due to movement. So am I looking at a new TC?

If I am I do have a donor Jeep, however it's a 92 and mine is a 90. Are the splines the same or is one a 27 spline and one a 29 spline?

27 spline vs. 29 spline applies to early vs later chrysler 8.25 rear axles. What you mean is are both transfer cases the same input spline count: the 1990 with automatic tranny is 21 spline input, the 1993 with automatic tranny is 23 spline. Go to Advance Adapters or Novak web sites for more info on splines and early versus late gear cut- BOTH spline count and gear cut style must match. That said, it is not too difficult to remove the input gear from your old t-case and put it in the new one, if the 1993 uses the same (earlier-style) gear cut. I don't recall when the switch in gear cut occurred.
Are you sure the transfer case is shot? Is the linkage out of adjustment? The chain loose (look through the fill or drain plug hole)? Any metal fragments in the fluid? A bit more diagnostic effort is needed to be certain what you are dealing with.

OK now I'm confused with this spline crap, input spline. Not to sound like an idiot but could someone draw me a picture...lol

As for the linkage, it doesn't look like it's ever moved since 1990 based on rust buildup..lol that and I couldn't tighten the bolt anymore than it was already. I attempted looking through the fill hole but couldn't see anything. The transfer case is the only thing I can think of that would possibly be causing the issues I'm having. I know it's not U joints, the only other thing that I can see...or rather feel is that when I grab the front DS I can spin it a little in either direction with my hand but it's just a little bit of play.

Anyone?

pop, definitely sounds like a chain.

recheck your vac system.

But b/c the shifter messings fix it... id def say tcase....

find a used one... swap it otu... bout the best I can say

I perminantly locked the front by spacing the fork over with washers so it doesn't rely on the vacuum anymore. I'm really thinking transfer case as well, I guess i'll have to swap over the one out of my freinds parts truck the only thing is that it's a 92 and mine is a 90 so I guess it won't swap right over eh?

Find one from an 87-90.. or swap his trans and transfer case over.

Fuckin truck....


I fixed it :wierd: