1990 XJ

I am brand new to the Jeep thing, I just purchased my first one today for $750. And I love it already, as of now what is wrong that I have found: 1.) 4wheeldrive does not stay engaged. 2.) Rear-end does not lock up pulling one leggers, i.e. I have a 1 wheeldrive 4x4 3.) Engine takes a little to start, cranks over after about 15seconds. I love this thing to death even if it dies on me it only cost me $750 but I am really looking at turning it into an awesome trail rig with atleast a 6'' lift and 35'', with bumpers, whinches and the works. Where should I start first? As I figure the rear end needs fixing but isn't that big of deal I am going to put manuel lockers up front so the 4x4 isn't a big deal, where should I start from? I think you are the best bunch to ask this question not the guys at my shop.

Tyler

Ok let me start... welcome to the jeep world..... the transfer case poping out i have to figure that one out, and for the rear it has what you would call a open rear which means only one wheel drives and for you want to do, svae your money up and do it the right way trust me i probaly lost over a grand destroying shit because it didnt work but daont worry you dont need much money to have a good time with the jeep, I have probaly less then 3 grand raped in mine.... also for the motor, it is a old jeep engine most of them do that.....

so a new tranmsfer case and weld the rearend?

FlatBlack1990 said:

so a new tranmsfer case and weld the rearend?

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You don't need a new transfercase. Do you have a vacuum disconnect front axle? If so that is most likely the root of your problem. As far as welding the rear...I wouldn't do it if your going to be daily driving it, especially in the snow.

i would not weld the rear either but it's not about the snow really... welding the gears makes it 100% locked all the time just like if you had a detroit locker. but a detroit isn't going to blow up, if a weld fails on any part you welded your whole rear end is toast! it will probably lock up and everything. do it the right way or don't do it. if you don't know if you have the vaccum disconnect front axel the chances are if it's a limited edition you don't, this has the (selec trac)NP242 transfer case btw which has full time and part time high gear, full time can be used on road but only use part time on loose surfaces. if it's a Laredo edition you probably do have the disconnect and it's the NP231 transfer case. you need to know a few things about your jeep before you jump into a project to accomplish 35inch tires. like if you have the dana 35 axel and you put a locker in it with 35" tires your going to break the axel and have wasted your money on the locker. the first place to start though is the suspension. it doesn't matter if you have all the traction in the world if you can't get over thigns, then the tires that you just made room for followed by or at the same time gears and if you want lockers. no point in haveing an axel torn into more than once, especially if your paying a shop.

Actually, welding a diff is nothing like a detroit locker, its like a spool. Major difference between them. In theory, the detroit is only locked when power is applied, and it should let the outside wheel freewheel around corners if you coast. Its not perfect but its far from a spool.

Just an FYI.

snow is coming in about a month so i guess i wont do that option, I'm not sure which model anything I have, I just checked and there is a vacuum line and it is connected at both sides. i had my wife check the mechanical aspect while i was under it and it all worked. I'm a jet engine mechanic but I cant figure out cars for the life of me, you'll have to stick with me I'm an idiot but I am trying.

I would agree with replacing the axle if you're going with 35's. There are many venders who supply custom axles and will build them for you, but it'll cost more. The hard start could be the old style "Renex" fuel injection system. I had a 91 that did the same thing, but it ran great so I just lived with it. If it were me building up to 35's I would start with the mechanics first. My feelings are that I would rather put in tha rear axle, and fix the 4x4 first, that way you could do the lift and tires and not worry about if the rear is going to snap when you're powering through that Alaska snow. I've owned 5 XJ's and I love 'em, welcome to the addiction.

Mr Miller, what do you think my 4x4 problem is considering you have had 5 of them, any problems like I am describing in any of those?

:repair: Get it running correctly 1st. :repair:
Go to your local parts house and get yourself a Hanes, Chiltons or better yet, a Mopar repair manual; them read it.

Like others have said, a stock 4X4 is only 4X4 if all four tires are on the ground and have equal traction. As soon as one tire from either or both axles loose traction power is shifted to that tire. This may be why you think your xfer case is not working.
If either of your front tires are pulling you along...it is working.
If it is not locking in, and you do have a NP231, follow the vaccum lines from the axle all the way back to and on top of the xfercase. Make sure that the connector is fully seated and not cracked. If it is hooked up properly, make sure you have good vaccum. This is a starting point.
Report your findings here.

Once you get what you already have running correctly, then start your upgrade.

My $0.02 - Do not weld the rear diff; get a locker.

on your extended cranking issue get a fuel pressure test guage and see if it maintains pressure when you turn the key if it bleeds down that is probably due to the enternal check valve on your fuel pump

Renix motors are notorious for extended cranking time...try cranking it over for a couple of seconds...turn the key off and on...crank it some more.

The 4x4 problem...Does the dashboard indicator light come on when you pull it into 4 wheel?? Does it not come on?

Try taking the small vacuum box off the front axle and sliding washers over in place to keep it locked in. The front axle will only be engaged when the tcase is in 4WD so you won't be full time. I'll try to find pics of it, or take mine back apart and take some pictures to show you what I mean.
All the 90xj's I've ran into start hard, including mine.

Got a hanes repair manuel today and I plan on taking some leave once I get a little bit more money to fix what I break when I tear into it. I think I am going to try to repair the 4x4 first so that I don't get stuck like I did yesterday on flat ground coming out of a mud hole. I've been looking into lifts and I think that I will only need a 5" lift instead of 6" just with a little cutting and maybe 2" body I would easily clear some 35" tires. Thank you all for the help and showing me that Jeep guys really are nice guys.

I want flame you this time sense you are new. But if you haven't looked under your XJ it is a uni body. Don't go into shock! Set down for a min and cool off. It will be ok. But don't mention a Body Lift again. The only way to lift an XJ is to use a suspension lift. Maybe you was talking about rear shackles and 2" rubber spacers up front. But that is still a suspension lift. Good luck with your future project.

yeah the spacer up front and shackle in the rear, I think of that as a body lift sorry, I have a 99chevy and a 95 yukon so thats my basis on lifts.

ohh one more quick question; I was looking into D44's and I saw where you can just buy the gear instead of the whole pumkin, is there any difference? Dana gears for $145.80 seems good to me but then again I'm a newb.

Don't be so happy with us just yet, we're really not all that nice.
My advice, to start with, is get underneath your new XJ and get to know it intimately.
Stay under there and don't come out for at least 45 minutes.
Look at everything. Feel things. Shake and bang on parts. Don't forget to take a rag!
My next advice would be to find and buy a factory service manual and use the Haynes manual to level a table with.
Finally, use the search feature and look up everything BEFORE you ask specifics.

Welcome to the board.
Stick around and become a member.
And lastly, don't take us too seriously, but take our advice to heart.

FlatBlack1990 said:

ohh one more quick question; I was looking into D44's and I saw where you can just buy the gear instead of the whole pumkin, is there any difference? Dana gears for $145.80 seems good to me but then again I'm a newb.

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Again, stick around and utilize the search.
As for the D-44, that's an entire axle swap, not just the gears.

Hey, I am new at this jeep thing also. Your not alone.
Just bought a 91' XJ for $350.00. Time to start having fun.

What is the max lift height before buying new control arms.
I have a 3" lift here but, should I go ahead and install coil spacers w/shackle kit at same time or not bother.