Mag90XJ

Hey guys this is my first post but I've been creeping for a while on the build threads, Especially Project black sky which I was very sad about what happened I wasn't even around the forums or jeeps when it happened and I was still saddened by it. but this forum seems like its full of great people and that's something to appreciate.


Anyways I've always wanted a jeep, I currently own a 1971K5 Blazer but that's too collectable to really take out and enjoy without getting white knuckled when your in technical stuff.


So along came the 1990 XJ 4.0 renix with 148000 original miles, the previous owner originally wanted 2.6k for it and I talked him down to 2k its got a tad of body damage but it came with a lift already and 33's so I figured what the heck, its something I can buy now and improve and if need be maybe sell for a tad bit of a profit or something to keep and wheel.


So the first issue I really had with it was the heating issue most XJ's have on the highway, over heated a tad once and I think it was because the electric fan relay went out. I've recently replaced it and haven't had any issues since, but of course I haven't taken it back on the highway yet either.


Just to really make sure that I knock out the overheating issue I'm going to do a complete flush of the coolant system and replace the thermostat with a 195 degree one, and a new high output water pump as well as the upper and lower radiator hoses and the correct Mopar coolant.


so that's really the major improvement I've done so far and I should be doing it this coming sunday, Im also going to order 5 brand new general tire AT2's keeping the 33's.


With all that being said I've only really worked on GM products and old ones at that 80 year models and back, so if you have any info about what to really check out and go ahead and replace on the XJ lemme know, and I'm very open to constructive criticism.


I've also ordered a roof rack that should make it look and function better for offroading for when I get my high lift jack, shovel, a few jerry cans and all the other extra parts and equipment I would need for recovery and prolonged excursions. I've already checked out the brakes and they all look great, Oil looks nice and clean, Coolant is rancid so its being replaced this weekend. Transmission shifts fine and the fluid looks great. Another problem I've had was the Transfer case failing to disengage I looked some stuff up and figured it out.




Anyways, any tips and tricks. helpful hints would be great!

PNWjeeper

https://www.cherokeeforum.com/f51/cr...x-tips-153657/
Great stuff for renix XJ's do it all in the cruiser54s mostly renix tips link above. The ground refresh is a must for all Cherokees. Welcome to the forum.

Mag90XJ

yeah man I read most of that last night it really covers a lot that I didn't even really think about! I appreciate it!

cruiser54

Begin with 1,3,4, and 5.

Welcome

Oswalla

You will find the weak spot in the cooling system is the pressure bottle and cap. I went through many, I suspect cheaply made after market parts mostly. OEM parts are getting scarce for renix era. A search for a metal after market bottle that someone came up with might be in your future, an option anyways.

TPS does not like water. Learned that the hard way cleaning up mine years ago when I first got it.

Give the front suspension a good look over. Trac bar upper heim joint tend to wear out and get sloppy. Grab bar and push up and down, if loose replace. I actually had to replace the mounting bracket, the hole was so wallowed out from neglect. Control arm bushings. I got my jeep from a friend and she never left pavement and these parts were toast when I got it.

DFlintstone

I have 2 90"s, one at 280K and the other over 200, both run great! (and clear 20 MPG highway. I just scratch my head when people post about their "Heap" breaking down often. Mine seem to just keep trucking on with very little trouble. Maybe they both happen to be "Wednesday cars" (when everyone is at the plant and no one is hung over, or maybe by 90 some glitches had been ironed out.

The cheap wall mart green coolant seems fine to me. Mix 50/50 ya know. Welcome Btw!

Mag90XJ

yeah actually this weekend I snagged a radiator and the overflow tank from a later model xj for the open system swap I'll keep collecting stuff I need for it. And maybe one day tackle it, as for right now. I'm hoping new radiator hoses, new thermostat and new water pump do the trick.

quneur

Thermostat housing and gasket. And if you're doing that then might as well get a CTS as its on the housing.

DFlintstone

No need to change the CPS on the bell housing just yet. The temp sensor on the left side of the block can be tested. The sender for your temp light/gauge is left rear up top on the head.