Engine swap compatibility 2.5L '87 MJ

Here is the deal. The 2.5L 4 cylinder in my '87 MJ is dead, ~30 psi compression test. It is a 2wd shortbed and it has a 4 speed manual which I believe is the AX-4.
I need to go to the junk yard and get a replacement 4 banger but I am not sure what other Jeep models and years are compatible. I've been searching but haven't turned up anything too helpful. There are just too many options out there:confused1.

From this article and other posts I've learned that the AX-4/5 aren't really compatible with the AX-15.
http://www.novak-adapt.com/knowledge/ax5.htm

I would like to keep the same computer, transmission, intake and exhaust to make the swap as simple as possible since it will be my first attempt ever. I know the AX-4 and 5 aren't as good as the AX-15 but I really don't want to tackle that right now due to time and $$ issues. Thanks for any help. If you know of a good thread where this has been covered I would appreciate a link.

Posted a bunch of details on the engines you can use in this thread... it's a bit of a read though. http://www.naxja.org/forum/showthread.php?t=1032534

At least it's an 87 instead of an 86-down, so if you decide later to put a 4.0 into it you won't have to get friendly with any sheetmetal really.

kastein said:

Posted a bunch of details on the engines you can use in this thread... it's a bit of a read though. http://www.naxja.org/forum/showthread.php?t=1032534

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Cliff's Notes version:
The basic block and heads on the 86-96 are the same. The accessories and the intakes are different.

I would totally cut my losses and start out with a different platform like the guy in that thread did if this weren't an MJ.
If the engine blocks are really the same on all 86-96 2.5L MJs, XJs and YJs, then I should be able to find a replacement pretty easily at the JY. It looks like I should be able to keep all my current accessories, intake and exhaust manifold, TBI and computer and transmission and bell housing and swap only the block(head included of course). Please correct my if any of my assumptions are wrong.

sounds like a safe bet to me.

Agreed. I think I'm one of the guys who convinced you to buy that MJ for that reason, actually.

Still, even a swap isn't THAT bad, even swapping the entire drivetrain. I've pulled a drivetrain in less than a day before and that was in 3 inches of mud, with the wrong tools, and involved cutting the entire jeep up afterwards. Even if it comes down to it you could pick up a rusted-out or totaled 87-90 XJ for a few hundred and swap the drivetrain and engine wiring harness and probably finish it in a good weekend.

If I can find a cheap donor with a decent engine pretty quick then I'll do the entire drivetrain swap. It would be great to have a 4.0L and 4wd. If nothing comes up too soon I probably go to the JY and get another 2.5L. I think I can get an engine there for $185 without the accessories if I pull it myself. It sucks trying to do stuff on the cheap!

OkieXJ said:

If I can find a cheap donor with a decent engine pretty quick then I'll do the entire drivetrain swap. It would be great to have a 4.0L and 4wd. If nothing comes up too soon I probably go to the JY and get another 2.5L. I think I can get an engine there for $185 without the accessories if I pull it myself. It sucks trying to do stuff on the cheap!

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too bad you're not close to me. I'd have sold you a complete 4.0 drivetrain with the renix ECU to save another MJ.

87manche said:

too bad you're not close to me. I'd have sold you a complete 4.0 drivetrain with the renix ECU to save another MJ.

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Man, I wish there was somebody like you around here! I promise not to send it to the scrap yard no matter what my wife says.

OkieXJ said:

I promise not to send it to the scrap yard no matter what my wife says.

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:thumbup:

Hopefully she likes it... or will once it runs. So much more useful as a daily driver than an XJ :eyes:

kastein said:

:thumbup:

Hopefully she likes it... or will once it runs. So much more useful as a daily driver than an XJ :eyes:

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That is totally the plan. She is "attached" to the XJ despite it being a heap so I hope to accomplish the same thing with the MJ. That is the motivation for the cheap solution. It will be very handy to have a truck around as well which everyone should be able to appreciate.

This project has been pretty stagnant but it does still exists.

I have a line on a 4cyl from a 95 YJ with 150k for $150. Will this fit? All I am concerned about it getting this thing running so the high mileage does not concern me. So will it fit into my 87 MJ?