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How to choose parts and what to prioritize?! New to my XJ & wrenching.


NAXJA Forum User
Central TX
TLDR- new to all of this. This XJ will surely outlive me at this point when I am done restoring it so... Where do I start? Is there a thread or 5 that someone can point me to about how to know what parts are reliable and basic maintenance process/order of operations on the XJ in general? I can search all the terms (and have) but the words "thermostat" or "radiator" for instance come up a lot. It is a lot to wade through.

What is worth good $$$ and what is ok to go cheaper on - my main concern is simply what part can I trust? Quality over price is my general go to for OEM or slightly better than OEM parts.

Full version- I am super new to wrenching and a new to me XJ, a 1999 SE spec with 4x4, 4.0, all the skid plates, fully manual/basic interior, no mods/all stock, 39,xxx miles. Built 10/98 and I have the build sheet. Definitely many more hours than miles because it was a university campus vehicle in Texas that some guy probably sat in a lot with the AC on. It has a dirty but solid interior aside from the wrecked headliner, paint is pretty damn good, and crucially NO RUST. None. I have not pulled the carpets yet so there could be some hiding in a floor pan but it was parked under cover for its whole life, too.

I HAD MECHANIC - replace head gasket (+ fresh oil change) and serviced rear diff (full synth) to get it into workable order before I dive in.

I COMPLETED - fan shroud, big 7 wires and headlight harness upgrade.

My XJ runs pretty good, fires up reliably (with a squeak when its its cold every 3rd or 4th start), but has intermittent rough idle and gets REALLY bad mpg for how stock it is on 215/15 tires. Overheating on a hot day in stop and go with AC on happened once now ... so general maintenance should help these a lot. The intent is a mostly stock weekend camping and trail head reaching kind of vehicle, so I never intend to go hard into wheeling or mudding. I have since come to realize since I bought it that these are hard to find in the overall great and unmodified condition mine is in.

How do you tell what OEM or slightly upgraded OEM parts are the go-to for any given item?... even with tons of searching forums it just seems like too much to sort through with so little experience!

So I go to look at parts, there are a million options for everything (pros and cons, right?) but the hard part is these options come with people's opinions ... so they vary from "NeVeR uSe ThAt PaRt!!1!!!11!!!" to "I used it and it is great," to many items just not having reviews or being obvious low cost junk. But MOPAR parts seem to be, usually, a rip off, too?!

#1 full coolant system flush (badly needed), absolutely job #1
#2 full tune up (plugs, wires, distributor rotor/cap), more?
#3 a rad cap, 195 thermostat/housing/gasket, maybe a water pump?, (has new
ish radiator with only 6000 miles since 2017 but maybe it should go?)
#4 clean the injectors and throttle body,
#5 transfer case, transmission, power steering and brake services.
#6 grease joints and replace any rubber mounts/stops that need replacing. None
are too bad but all are 24 years old.
#7 should probably replace a few sensors, too. Not sure which ones are reliable
and which ones wear out more easily? O2 and TPS? Intake air temp?
#8 less important is the suspension. Leaf springs are flat,
front coils are dead, shocks are worn out. But engine first.
#9 Needs a damn radio and speakers. All dead.

It will all take time, not looking for it to be done ASAP.

Thanks to NAXJA for being a great learning resource for the last 5 months so far though!
First off, this probably belongs in OEM Tech. More folks will see it there.

For most of the things you have listed on your to-do list I don't have any strong opinions one way or another, but there are some parts where yes, it does matter.

Thermostat: Go the to stealership and get one there. That is your best bet.

O2 Sensors: NTK

Other stuff, work your way through and figure out what is good and what is not. I would flush the radiator before I tried replacing it. I would send out the injectors and throttle body to someone who has the equipment to clean them well.

Fluid changes are just a matter of what you can get locally. I avoid Fram filters. The important thing is to simply change out the old stuff and get some fresh fluids in there to get rid of the contaminants that have collected over time.

That is a remarkably low mileage XJ. Take good care of it.
X2 ^^^

I’ll add, do the basics (plugs/wires/cap/rotor/coil), change all fluids and filtes, then just drive it. Check and replace motor/trans mounts, do a good once over on the suspension bushings (sway bar links, control arms, etc)…

As for parts, for a daily driver the name brand stuff is plenty good enough for most people. I would suggest very few things aftermarket over stock for a daily driver.

Feel free to have a look at my buils thread, i was in your shoes with mine when i bought it a year and a half ago…similar thinking, replace everything and get ahead of the gamr, upgrade where theres a known issue, etc.

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Still struggle with the concept of OEM parts for vehicles this old. Here, I doubt you could get KJ parts from a Jeep dealer - assuming you could find one.

Not a problem for me, because I've never used OEM parts (unless there was no other choice) generally they're overpriced generic parts in very expensive boxes. Ignition parts are best bought from whoever has a leading ignition part brand's products at the best price. Holds good for brakes, clutches, electrics, et, etc although the leading brand of, say, sensors may be more difficult to identify.

Plugs are a little strange because there is no overall best make, as engines seem to have their own preferences. Jeep 4.0's want Champions but, apart from some, probably, pre-'70 British cars I wouldn't use them in anything else. 3.7 V6's & 4.7 V8's like NGK's, as do city driven Ferrari V12's (although Ferrari specify Champions - & supply them in their own boxes!), and Rover (ex-Buick) V8's although they seem to be equally happy with Bosch plugs: rule 1 - know your engine.
Ok, thanks y'all! I will definitely try reposting a version of this on the main OEM Tech thread, too. I think I tried posting them too close together with the same title so auto-mod probably nixed it.
If the motor oil was not routinely changed and if you decide to replace the water pump and radiator, then I recommend replacing the timing chain as well. Only a few more things have to come off to get access to the timing chain.
If the motor oil was not routinely changed and if you decide to replace the water pump and radiator, then I recommend replacing the timing chain as well. Only a few more things have to come off to get access to the timing chain.

Not heard that one before, but can see the logic, particularly if near (or past) the recommended mileage to replace - although don't recall seeing that anywhere.