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88 4.0 to 91 HO Would you? Pro's/Con's please elaborate.


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Just found out my cousin has a '91 cherokee 4x4 4.0 HO Aw4 and i think dana 44, havent gotten the mileage yet but was running a year ago(inherited then parked)

Question: Would it be worth it to swap the engine/drive train and all other goodies into my '88 mj 4x4 4.0 Ba10? What all would swap and make since to swap? Oh yeah and its free! Well almost free, gotta take the son deer hunting! where is the down side?! I would love the idea of having an automatic. He!! i havent even gotten the MJ started up as is yet! Prolly gonna continue with that for now and see what yall think about the swap option.

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The HO makes more power at higher revs than the Renix but the Renix is somewhat better at the low end. (224ftlb @ 2200 for the Renix vs 225ftlb @ 4000 for the HO) although the HO engine still has more than enough low end torque. The real benefit to the HO is easier to find parts, (limited) diagnostics, and less electrical trouble, although I'm not sure if swapping HO electronics over is worth it when you have Cruiser's Renix tips.

 

The AW4 is without a doubt a more reliable trans than the BA-10 is. The AW4 can be made to work. I'm not sure how much of the AW4's wiring you'd need to deal with.

 

Of course, if you just swap the HO engine and keep everything else the same (you can relatively easily swap an HO engine in while keeping the Renix setup), it'll pretty much perform like a Renix engine.

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Here's what you need to know:

 

Cruiser’s HO into Renix Swap
 
This swap is easier than some will lead you to believe, generally those who have never done it. Those of us who have done it, like myself, will share with you the things that need to be done for a successful swap. Just think of it as swapping in a long block.
 
The HO and Renix have some differences but none that can’t be overcome very easily.
 
Any HO engine from an XJ or ZJ through 1999 can be used. One running change was that the rear of the head was no longer drilled and tapped for the temperature gauge sender beginning in the 96 model year. The sender can be relocated to the threaded hole in the thermostat housing taken from the HO engine. You’ll have to extend the wire to that location. Some brave souls even drill and tap the HO head for the sender.
 
You will be using the intake and exhaust manifolds from your Renix, along with all your sensors and wiring. Since the intake ports of the HO are slightly different, you use the Renix gasket. Exhaust ports are identical.
You will need to use your Renix distributor as it is different than the HO because they use different fuel management systems. The  flywheel or flexplate from the Renix must be used so your CPS gets the correct signals. The valve cover from the Renix allows you to keep your CCV system intact and requires no modifications.
 
The HO block will have a plug in the coolant galley on the driver’s side of the block, closest to the front, which needs to be removed so your Coolant Temp Sensor can be installed in it’s place just as it is on the Renix. It requires a 5/16” square drive or a modified 3/8” drive that has been ground down to fit. Do this before installing the engine.
 
As for the knock sensor, which is located just above the oil pan on the driver’s side of the engine about mid way, all the blocks I’ve seen are threaded for it. If not, I’ve heard they may be drilled but not tapped. Tap the hole if that’s the case.
 
 
Revised 03/28/13
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First thing I did when I got my 88 Chief was to swap it over to a 91 harness and motor...... the pile of vacuum lines and canisters I had left over was staggering.  Nothing is simpler to work on than a HO harness and motor...... and in the woods or on a rock ledge nothing is more reliable.  Nice thing about the 91 is it's a crossover year and most of your stuff will plug right in.... column, wiper motor.... ect.  Swap in that 91 hardware and AW4, you'll have a long weekend in the job but you'll be glad you did it.

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I have done this exact Swap in my 89 a few years after I got it as the Renix engine I had in it was bad...

 

AS said it is easier then people make it out to be and nearly plug and play...

 

In My case I used a complete donor XJ and I think it was a 93 XJ and swapped everything in from the XJ to the MJ, dash and interior harness as well as engine and engine bay harness and the Only issues I found were...

- Need to adapt the MJ Rear Harness to the Newer XJ harness which again was not that difficult once you identify each wire in the XJ harness and the Rear MJ harness then cut and splice and away you go

- Fuel pump resistance is opposite so if you do not address this then when the fuel gauge is empty its actually full and full is empty... (I used a Brand new 93 XJ sender and Cut and modified it to become a MJ sender)

 

I ran it like this for a few years then did the 97+ Conversion and OBDII Swap which I like a lot better...

 

I would say if you do not want to do the 97+ conversion ever then the OBDI is worth doing over the Renix system just expect to be down for a while as You learn as you go...

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This is great kindlin for my fire everyone! Haven't been up to the shop for days and it's killing me. Left to ponder all the possibilities my wrench finger is gettin itchy... Same thread additional question:

If the renix 4.0 currently in the MJ turns out to be solid enough to rely on(haven't even cranked it yet) am I off base from what I think I have read that the '91 4x4 Cherokee AW4 and the TC its married to, would bolt right in to replace the BA10/ np231 in the MJ?

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  • 1 month later...

Ok pulled the Cousin's Cherokee home on a trailer today. It's a '92 Cherokee Laredo 4x4 aw4/np231 d30/d35. 242,xxx miles. Very straight and clean body, interior is not so great but not toast. It's Rollin 31x10.5x15s with less than 20% tread. Lower dash was loose and looks like someone's been tinkering. Engine bay looks good but right off I noticed the front lower exhaust manifold bolt is missing, hmm? So I've got some thinking to do. I still really want to run an auto in my Chief. I know the ba10 is covered in oil but until I put some miles on it I can't say its shot. However, the future called and said it would like to see a 4.5" lift, 33"s, an automatic and a re-gear(4.10 or 4.56) and if possible the 97+ conv. This begs the question- Is it worth trying to mate the '92 aw4/231 with 242,xxx on it to my renix or pass this buggy on and get to lookin for an auto 97+?

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Well it kinda depends on how much work your willing to do..... do some research around here and you'll quickly realize that hanging a 97+ dash is not a simple task.  When I was on the fence about this very issue I just did a quick pro's and con's sheet listing what I was gaining versus what it would cost in time and labor.  People can say what they want about OBDII but I've owned a 98 XJ, my son currently owns a 2001 XJ... my brother has 5 97+ XJ's and works on Jeeps for a living and I'll tell you from experience that these systems had alot of gremlins.  I had them so bad in my 98 that I swapped the entire harness just to fix my problem.  So back to my pros and cons sheet.... there were alot of cons... modifying the firewall, buying a 97+donor vehicle, new mounting tabs on the firewall... ect...ect and only one pro and that was a newer style dash (I also had an interior cage to consider) So in the long run I kept my dash and just upgrade my console to a 97+ and some GC seats..... I know alot may not agree but these are my opinions from my experiences..... :yes:

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Well it kinda depends on how much work your willing to do..... do some research around here and you'll quickly realize that hanging a 97+ dash is not a simple task.  When I was on the fence about this very issue I just did a quick pro's and con's sheet listing what I was gaining versus what it would cost in time and labor.  People can say what they want about OBDII but I've owned a 98 XJ, my son currently owns a 2001 XJ... my brother has 5 97+ XJ's and works on Jeeps for a living and I'll tell you from experience that these systems had alot of gremlins.  I had them so bad in my 98 that I swapped the entire harness just to fix my problem.  So back to my pros and cons sheet.... there were alot of cons... modifying the firewall, buying a 97+donor vehicle, new mounting tabs on the firewall... ect...ect and only one pro and that was a newer style dash (I also had an interior cage to consider) So in the long run I kept my dash and just upgrade my console to a 97+ and some GC seats..... I know alot may not agree but these are my opinions from my experiences..... :yes:

There you go again

 

Speaking from experience....LOL.

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