I'm new to the jeep world and trying to fix up the 90 xj i got from a freind. I have a tuner car and bought the jeep to drive through the winters in colorado. A friend of mine built the truck but it was neglected a bit and i'm just trying to get it trustworthy enough to have some fun this summer.
I have been reading alot of forums but dont know why many dont like renix models. Since I already have this truck and am will to spend some dough to fix her up...what can I do to get this rig right? I have been taking care of general maint stuff, new pwr steering pump, water pump with low temp t-stat, harmonic balancer, idler pully, serp belt.....what are known issues with this yr jeep? I have been thinking of buying reman motor and tranny. any input welcome Thanks for the help.
4"rusty's lift
pro comp shocks
rubicon lower cont. arms
33" BFG's

 

There's absolutely nothing wrong with the Renix motors! They've proven themselves time and time again with their incredible track records.

IMO- The Renix is just as good as the H.O.'s... and the Renix's seem to get better gas mileage!!!

 

I love my renix!

...Just wish it didnt knock like a ticking timebomb...

 

are there any things I should know about or look for? As I said i'm new to jeeps, i am mechaniclly inclined and can do the work but dont know what problems they are prone to have...truck has 192,xxx but feels strong, runs doggy when I get up to altitude in the hiils tho

 

it just doesn't have the power that the later fuel injection jeeps do. they had only about 177 HP and 220 ft-lbs of torque, and the later years went up to 190 HP and held onto the same torque specs. the ones after 1996 though had 5 additional ft-lbs of torque added to them, but other than that, there were very few changes to the engine. the inline engines are just hearty and reliable, but were ever the power goes, that's where most guys will flock to.

 

It is recommended to run diesel oil, Most recommend Rotella. Modern oil is low in Zinc and causes cam and lifter wear, diesel oil still has enough zinc to keep parts from wearing.

The front vacuum disconnect can be problematic and will leave you stuck in the simplest of situations in the winter (ask me how I know) This is what I did to mine:
https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/

You can also buy a "Posi Lok" system, but theyre like 200 bucks.

If it hasnt been done, do a tuneup. Include cap, Rotor, Wires, Spark plugs, and Oxygen sensor.
There is no CEL, but they are very easy to work on and diagnose with a Multimeter and some time. The oxygen sensor should be replaced every ~80-100,000 miles.

 

A large portion of people dislike the Renix due to a lack of brainless slap on modifications that supposedly add "power".... and another percentage don't like it do to the fact you have to actually spend some time and use your brain to diagnose issues with it.

Who cares about HP numbers... If you are wheeling its all about torque.

 

Like I said, I love my renix. Just wish it didnt sound like a ticking time bomb.

Two of the reasons why I LIKE mine..

 

bio has over 340,000 miles...still getting good oil press,
has healthy fuel appetite.
getting tired, but I love her
Thinking stroker for the rebuild

 

There is not a damned thing wrong with RENIX - other than failures of maintenance.

The engines were built by AMC through mid-1988, and AMC castings were used through about mid-1989 (then Chrysler cast the parts, and Chrysler OBD-I compliant electronics replaced the Bendix-built jobs for 1991.)

The control systems were built by Bendix/King - the avionics division. I've heard of three ECU failures, and I have two of them (one from South Africa, one from Nebraska.) The third one was in Czechoslovakia, and it had the same failure as the other two - fuel injector driver transistors. The Czech is a better electronics tech than I am, and was able to sort out a repair faster.

Most people (particularly those coming from the "tuner world" and the "new mechanics") get all screwed up because RENIX is pre-OBD. However, that's probably the strength of the system - just about all of the troubleshooting needed can be done with a DMM. There are a few places where you can get the TSM for RENIX - I know that Pirates of the Rubicon has a .pdf in their Tech section, and I keep a copy available in my RENIXPower group (groups.yahoo.com/group/RENIXPower. If that URL doesn't work anymore, search Yahoo! groups for RENIXPower. It's still mildly active, but Yahoo! went and changed their URL format for the groups.) Download this manual, print it, and keep it handy. I printed mine on light cardstock (about 40# weight) and had it coil bound to keep out in the garage.

NB: Both of these - and most other sources online - have a duplication of one page in the high fifties, and the page that is occupied by the duplicate is eliminated. I'm working on finding a copy that is compleat, and I'm also trying to get Actia Corp (the last known RENIX patent holders) to loosen up with some of the tech information. Hell, the system's been out of production for twenty years now, y'know?)

I've had five RENIX XJs so far, but I came up on points & condensers - I'm used to doing my own thinking. I'm not a "parts monkey" that works from the codes, and takes OBD DTCs as Gospel when it comes to diagnosing faults (they just tell me where to start looking...) So, the system is compatible with my own thinking as it is. Took me forever to get used to OBD - and I was able to troubleshoot a problem about as fast as - and a bit more accurately than - OBD-I anyhow.

Given a choice, RENIX is my favourite. OBD-II is second, while OBD-I just plain sucks (why? California Air Resources Board and CalEPA spec'd OBD-I, SAE took over for OBD-II. Therefore, OBD-II is an industry standard and makes rather more sense. California can't get anything right - look at all the budget trouble they're having out here now!

(No, I'm not a Californian. I consider myself an "expatriated American" out here...)

The principal "problem" cited with RENIX is the "closed" cooling system. However, properly maintained, there's not a thing wrong with it. Spec operating temperature for the 242ci I6 (all years) is 212-215*F, although I've been able to pull my 88 down to about 185*F with a little work. The only actual problems with the RENIX cooling system are:
- The OEM radiators tend to shoot crap at about 150-180Kmiles. This is normal - replace with an aftermarket unit, flush biannually, and you're good.
- The "football" tank up by the firewall is plastic, and holds pressure (16-18psig.) Replace it every six or seven years - you can get a new tank with a new cap for a decent price from Morris 4x4 Center. You can also get a metal replacement from, I believe, Mac's Radiator - but it's spendy. I'm also working on an alternative for that...

Other than that, the only issues are common to all cooling systems - rubber hose longevity, coolant longevity, &c. I've taken care of most of the hose longevity issues (see attached pic - I was tired of buying all of those moulded right-angle hoses...) the coolant longevity is two years - just like it's always been, and you get the idea.

Besides, if the "closed" cooling system is so bad, why is it enjoying a resurgence in OEM? I had a 1992 Corsica that had it - ran 187-190* all day long. Got a 2005 Verona that's set up that way, runs 190* all day; rain, snow, s**t, or mud. Keep the system flushed, the coolant fresh, and the radiator fins clean; and you're good.

The copper heater plumbing is not a new idea for me - I've done it before on several vehicles. Took me about a half hour to stomp up from stuff around the shop - I'll refine the measurements as part of my refit. The hose bibb adapter is there for backflushing, and the valve is there to force reverse coolant flow (I used to pinch off the hose to get that result, but you can't pinch copper line very well.) Even if you don't want to do the valve, I do suggest you solder on the hose bibb adapter.

And the plumbing is coupled to the vehicle and engine fittings using short segments of 5/8" or 3/4" heater hose (size PRN,) as "vibration stubs.)

Nope - not a damned thing wrong with RENIX. Parts are getting a bit scarce, and I do wish CA would let me dispense with the EGR setup (it's not really needed on this engine - low compression. I've got reports from CA Smog equipment that say the engine runs cleaner without the EGR than with - if I could eliminate the EGR, I could probably also eliminate the catalytic converter as unnecessary. Would be interesting to find out...) But, it's about as reliable as a rock, and I see no reason to replace it.

 

they're all great motors. don't listen to the ones that say power tech owners are dumb, or renix owners are smarter. you have to be mechanically inclined to work on any vehicle out there. otherwise just sign over your paycheck to the mechanics. forums have made fixing your vehicles about a billion times easier. get what you can like or afford and use it in good health. as with any used vehicle, keep up the maintenance. i'm sure it will love you for it. both renix and power tech motors last over 300k miles with regular maintenance, even with occasional abuse.

 

oops

 

I appreciate all the feed back, i was surprized not to get more grief for having a tuner car. have been taking advice and up till a few years ago was never a car guy and just paid somone else to change my oil b/c it was easier but as was stated earlier you can find just about any info you want to on this wide wide world of webs....hence my registration on this forum. So anything i dont know how to do somebody else out there has found a right way and a wrong way to do it so I'm glad you guys can save me some heartache here and there.
If just a few horsepower is what guys like or easy trouble shooting go buy a tuner, lol bolt on's = big HP and troubleshooting is windows based!
Like I said thats for all the info and keep it coming. When I found the t-stat housing flange was broke and RTV'ed up I put in low temp stat, it dropped temp considerably...its running 175 or so, is this a problem? I figured cooler ='s better...
And I'm a pipefitter so i will be runnning some copper lines, might as well make stuff last longer

Also i found a page somewhere that a guy changed his rear seal without pulling motor, is this an acceptable practice? one of my buddies was thinking somebody found this method by not knowing what they were doing, mine is leaking...not bad but i'm tired of leaving drips and they fall onto exhaust leaving an oh so lovely sent at stop lights.

 

OBD would complain about the low-spec 'stat, but RENIX don't care. In fact, my 88 is one of three vehicles I've heard of that won't run properly with any thermostat installed - it overheats within five minutes if I install one! I pulled it back out, and Beck settled down right around 205*F. And stayed there.

Not much other work I'd done, but it all helped:
- Make sure there's a "support coil" in the lower radiator hose. Even if you have to make one (CRES flat stock wound around a form will work for that. Use a largish wooden rod - not quite the ID of the hose, but within 1/4-1/2" or so.)
- Clean any casting flash you see from any openings where you can access the cooling jacket.
- Clean any casting flash you see from the thermostat housing. Ditto the water pump housing.
- Break any sharp corners anywhere you can see them in the cooling system; they'll cause heavy flow disturbances.
- Add Redline's Water Wetter to your coolant. It's a huge help!
- Make sure that your cooling system can maintain pressure. New RENIX caps have tested from 16 to 18psig - pressure test the system to 22-25 to be sure.
- I might even go so far, eventually, as to make "hardlines" for the radiator lines as well, and give them the same treatment as the heater lines. Then, just keep a stock of bulk hose on hand for repairs and service...
- Don't use tap water. Not even an "if you can avoid it" - just don't. Check the Army/Navy store, you can usually score water jugs there in capacity from five to twenty litres, and they're tougher than the hinges of Hell. I own several - I keep a 5L in the truck of my wife's car, two 10L in the back of my truck, two 10L in the garage, and a few 10L in the house (Hammerspace is earthquake territory.) Fill them with reverse osmosis filtered water (it's cheaper than distilled, and just as clean.) You can use R/O water in the radiator, in the battery, and in you without any complication whatever.
- Flush the system regularly - read: every other year. Every third or fourth flush, use the two-part acid/neutraliser stuff, and follow the directions Exactly. Except: add one additional flush clean, after the neutraliser goes through, using clean water only. Drain and refill (the block drain plug, on RENIX, is on the driver's side down by the exhaust collector. I'm informed it's threaded 3/8" NPT, but I haven't checked it out to be sure. I plan to install a remote-operated drain valve one of these days; for now, I just jack up the rear end and pull the water out with a wet-vac adapted to a small-bore hose and run down the water pump snout.) Replace the coolant after every flush (to get rid of old coolant you may either find a radiator shop - they'll usually take it gratis - or check the regs on your local water company. They may take small quantities poured right down the drain - San Jose Water will allow 1/2 gallon or less per month, per residence. Small jobs go down the drain, large jobs go to the radiator house - they recycle it there, so they don't mind getting more in.)

And naw, I'm not going to give you grief for coming from the "tuner world" - I came up on Chevvies, but I grew up myself (and worked on AMC until they became about as common as feet on fish.) Couldn't bring myself to work on "tuner" cars tho - especially since the market is such that any idiot can crank up the engine. Kinda takes the fun out of it - I enjoyed playing with the old V8s because you had to know some of what you were doing (at least!) Vic Edelbrock, Sr. made the SBC popular when he got 1bhp/ci out of the thing at Bonneville fifty years ago. But, I ended up with a preference for Gen II/III AMC and MOPAR - which doesn't have as great of an aftermarket (even Ford has MOPAR beat, and AMC has never really been all that popular. But the engines are hideously overbuilt...)

But, when I hear some tuner riceboi going on about how he's King Turd of S*** Mountain, here's what I end up thinking...

 

i like tuners...fun cars...i totaled my eg civic with jdm h22 and was heartbroken...then i found my jeep comanche(which is 2wd) and caught the bug!!offroading is alot more fun IMO...looking to get a XJ soon though!