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Late model TJ/XJ 4.0 in an MJ, any major hangups??

Safari Ary

NAXJA Forum User
Ok, I'm preparing for this MJ project and I'm trying to decide if buying 2wd MJ w/ a blown motor for CHEAP and swapping in a drivetrain is worth it. How hard is this swap if I get the ECU and TCU and wiring harness?? Can I simply swap everything from one engine bay to the other or are there other complications??

Also, I can get a complete 4.0/Aw4/231 w/ all the computers and wiring from a wrecked '97XJ for $2000. Is that too much?? Not sure if that includes shipping or not. Thanks for your opinions and experiences guys.

thats WAY too much.. one of my friends cam across a 4.0L with low miles for 200 bucks with a computer and harness... a rear 60 for 225 a front 60 for 800 .. and a t98 and d20 combo for cheap as well.. keep looking and if you need help let me know.. my people know people :D
$2000 sounds high, but $200 is more the price for a rebuildable short block, not a low mileage engine complete with tranny and wiring. I would look for the $1500 range, but $2000 is not WAAAY out of line, IMHO.

Remember that the MJ came out in 1986 and was just a version of the XJ. You won't easily drop a 4.0L into an '86. If you're looking at early MJs, keep to '87 and newer. '87 thru '90 will be Renix, so if you get a late model drive train you will need EVERYTHING, right down to the instrument cluster. It would be far better, I think, to find the MJ first and then buy and engine and drive train suitable for that range of years (i.e. Renix or HO). This is especially true if you expect to drive it soon. To rewire an early one to the late model specs means completely disassembling the dashboard and stripping out all existing wiring, then installing and connecting an entire new harness. Not impossible, but not my idea of a fun weekend.
Thanks Eagle, that's the kind of info I'm looking for. I'm definately gonna keep it to '87 and newer so that at least physically the 4.0 will bolt in. Can someone tell me the differences(i.e. years) of the long vs short block?? I've often heard people talk of this, but don't really know anything about it. Thanks

The "short block" and "long block" are just bad names that can refer to any engine. The short block is basically just a bare block, while a long block is a block with stuff like heads, timing cover, oil pan, that sort of thing. Ok, so I don't know exactly what's included in a long block, but I do know that the names don't refer to any specific engines sizes.
Jeep on!

P.S. and there's nothing terribly wrong with an 86 as long as you don't try to put a 4.0 in it. Just throw in a 3.4L chevy and away you go! Vrrrooooommm! At least that's the plan for my 86. :)
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