MJ Comanche Tech. Stock & Modified. MJ (86-92)
All discussion regarding the Jeep Comanche, the pickup truck related to the Cherokee platform.

89 MJ 2x4 to 4x4

Old 06-01-2014, 02:45 PM
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Year: 1987
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Default 89 MJ 2x4 to 4x4

I just inherited a 1989 2x4 mj from my grand mother here recently, and in honor of her I am going to build this MJ into a pretty sweet build. my plans are to paint it white and throw a mid sized breast cancer ribbon decal/paint on it (due to the fact that's what took her. but also to the plans is lifting it roughly 5.5 to 6.5 inches, dana 44s, etc.. but before I get into it head over heels, I was wondering if swapping out some Cherokee parts on it to convert it to 4x4. I have a donor vehicle, 1988 jeep Cherokee 4x4 I6 4.0l automatic (mj is auto as well) and I was wondering if I took out the engine, trans, and transfer case, would that be a direct bolt in or would I have to go with a newer xj donor for everything to work correctly? I know ill need shift linkage from xj as well as a modified driveshaft, but that's later on down the road. thank you in advance!! also any ideas you all would wanna throw out there would be highly appreciated!
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Old 06-02-2014, 07:11 PM
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Got everything you need except rear driveshaft.
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Old 06-09-2014, 01:15 PM
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Will I have to use the computer harness from the Cherokee in the swap for the mj or will I be able to use the mjs stock harness?
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Old 06-09-2014, 04:21 PM
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Originally Posted by 87xjnoob View Post
Will I have to use the computer harness from the Cherokee in the swap for the mj or will I be able to use the mjs stock harness?
Here's the answer:

Cruiserís 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 canít 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. Youíll 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 driverís side of the block, closest to the front, which needs to be removed so your Coolant Temp Sensor can be installed in itís place just as it is on the Renix. It requires a 5/16Ē square drive or a modified 3/8Ē 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 driverís side of the engine about mid way, all the blocks Iíve seen are threaded for it. If not, Iíve heard they may be drilled but not tapped. Tap the hole if thatís the case.


Revised 03/28/13
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Old 06-09-2014, 10:09 PM
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I think he's going 88 into an 89 no HO swap involved. Stock harness will work as long as he is going 4.0 to 4.0 he never told us what his original engine is.
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Old 06-09-2014, 10:17 PM
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Originally Posted by nitroxsteve View Post
I think he's going 88 into an 89 no HO swap involved. Stock harness will work as long as he is going 4.0 to 4.0 he never told us what his original engine is.
Could be.
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Old 06-12-2014, 06:49 PM
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Yeah, its just a 4.0 to a 4.0 swap, but also converting to 4x4. I'm looking at just completely gutting the xj (4x4 )and putting it all in to the mj which is 2x4 as of right now
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Old 06-14-2014, 11:09 AM
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Its all bolt on man im in the same boat. 88mj 2wd and my donor is 90xj both 4.0/aw4 you dont even need to cut a hole for the tcase shifter its already cut and just capped sheet metal and a few screws. Just keep your donor ecu and tcu just incase
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Old 06-23-2014, 01:53 PM
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Wiring harness might not be exactly the same. I swapped a 90 harness into my 89 and a couple of the connectors were a little different. If you don't have to pull the engine, then I would leave it alone. Although it might be nice if you are planing more of a full resto on it. That way you can freshen up all the ground and shady factory wiring for another 30 years of a great running truck.
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Old 06-28-2014, 05:33 PM
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I'm gonna have to replace the motor in it with the donors motor because the motor in the mj is complete crap due to years of neglect. Ex. Oil sender/pump, head gasket, etc.. I know I could replace small stuff like that, but I'd rather not tear into it if I don't have to. Also another question, the mj is one of the "on the column" shifters, and the xj(donor) is just right above the trans like every other xj.. Will I have to switch out the steering column as well?
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Old 06-28-2014, 07:55 PM
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You should not have to change anything other than the tras/tcase, front axle, and shift linkage for tcase. If you want or need to use the engine its a direct swap no harnesses need to be changed. You do not need the rear axle if the ratios match. You should only need to find a rear drive shaft. Its a fairly easy swap dont make it harder than it should be.

On the subject of the shifter on the column you can leave it there you will just need to find a cover for the tcase shifter from anouther column shift MJ.

Last edited by nitroxsteve; 06-28-2014 at 07:58 PM.
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Old 06-29-2014, 03:29 AM
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I cut up the the center console from my XJ to cover the transfer case shifter. It isn't pretty but does the job for now. With the floor shifter not there it acts as a cubby to put my toilet paper and sunflower seed in there for when I'm wheeling lol. I have been on the lookout for bucket seats for it so I can have the full center console Just curious do you have a bench seat or bucket seats in the MJ? Mine has the column shifter with the bench seat and was 2wd when I got her, she also has the crappy gauge cluster without the tach. I'm thinking most pioneer's came this way?
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Old 06-30-2014, 08:19 AM
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Mine is the bench seat as well lol. But the idea of somehow putting the two front seats of an xj in place of the bench
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Old 06-30-2014, 01:15 PM
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I have been on the lookout for an 89 2 door XJ at the junkyard, but it seems like XJ's are gettin harder and harder to find nowadays for me. Hopefully when I do find one it will have the tach gauge cluster also!!!!!
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Old 07-01-2014, 11:21 AM
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I would love a tach in there instead of a Freakin gas gauge that's just an eye sore. I might just install an aftermarket tach somewhere on the dash if it doesn't look too tacky. No pun intended
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