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Hey I'm new to the site and to MJ's so don't flame to much. I searched a little but found nothing. I just bought a 86' mj with a blown 2.8 I also just bought a 92' xj with a reman engine in it. Is it possible to swap the 4.0L into the mj.

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Hey I'm new to the site and to MJ's so don't flame to much. I searched a little but found nothing. I just bought a 86' mj with a blown 2.8 I also just bought a 92' xj with a reman engine in it. Is it possible to swap the 4.0L into the mj.

Hmm, you must of come over from JU ! Don't worry, its a lot saner over here. Welcome to the club! :waving:

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Thanks for the replys guys. For me the 2.8 to 3.4 is not an option as I would have to get a 3.4 and I already have a 4.0. So if I do this swap it will be to the 4.0. What differances is there to the truck it self? I have all the wiring the dash if needed, m/m, transmission, radiator. etc., etc. Jeeppintom the link you posted doesn't worky.

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It's never too late. You should easily be able to sell the 4.0L to raise enough funds for a 3.4L block. :D

 

But since you have a complete XJ, it is technically more possible than before. Get a shop manual for the 92 XJ. You'll need to swap in the entire drivetrain and wire harness and dash, plus the front sheetmetal (for the 4.0L radiator crossmember and hood latches) and hood.

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In addition to having to remove the radiator supports from the MJ and swap in the appropriate parts from the donor XJ, you will probably also need to "massage" the firewall. The firewall apparently is different on the vehicles with the 4.0L. Some reports claim you can hammer the firewall a bit to provide the necessary clearance, others say cutting is necessary.

 

The swap has been done, so it isn't impossible. Just keep firmly in mind that it is NOT a drop-in swap.

 

The polarity on the gauges is reversed from '86 to '92, so you really are looking at completely rewiring the vehicle to use the '92 injection and engine controls. And the 4.0L uses a higher fuel pressure, so you're also going to have to adapt the XJ fuel pump to your MJ fuel tank -- and reverse the polarity on the fuel level sender to work with the '92 instrument cluster.

 

Lastly, the '92 uses an electonic speedometer, and your MJ has a mechanical speedo. So you'll need to adapt that, as well. If you pull the entire engine/tranny/transfer case from the XJ and also use the XJ gauge cluster, everything should work together.

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