86 MJ 4x4

[gunner]

Hi everyone, i'm new to this site and was hoping someone could help me with some questions. I'm looking at buying an 86 comanche with a 2.5 litre 4 speed and 4x4. i also own a 87 cherokee with a 5 speed and a 4.0. I'm hoping to switch the 4.0 into the comanche. my question is that since 86 was the only year that a 4.0 litre wasn't an option, how difficult is it to swap the 2.5 out and which 4.0 would be best to use? Any advice would be greatly appreciated.

[Pete M]

With most years of 2.5L MJ you have to swap everything. Wire harness, trans/t-case, the works. A donor XJ is pretty much required. With the 86 model year, you also need to swap the radiator support, hood, and the hood latches to make it work. Minor tweaks to the firewall with a big hammer may also be necessary.

[gunner]

will the 4 speed bolt up to the 4.0? or would i have to swap in the five from the xj as well?

[Wildman]

No, the AX-4 will not bolt up to the 4.0, different bell housings, plus it will not hold up to the high torque of the 4.0, plus you'll really want to have that 5th gear with the 4.0, and 4.10 gears, if that's what your '86 MJ has.

 

Just about everything is interchangeable between the '86 MJ and your '87 XJ donor.

 

You'll need to strip the '86 right down, engine, wire harnesses, radiator support. you'll end up with an empty engine bay ;)

 

And every component from your donor will be transplanted into the engine bay.

 

The interior dash wire harness, and all sensors, controllers and ECU will need to be replaced.

 

This can be done easy with just swapping out the entire dash, or changing out just the wire harness from the donor.

 

The nice thing about this change over, is that just about everything is plug and play :brows:

 

The only issue you will have is the difference in the rear feed harness from the XJ to the MJ, IE: tail lights, brake lites, and this the only place you will need to splice the wires.

 

Oh, one thing I forgot, the hood latch is different from the '86 to the '87, from the center latch to the corner latches, easy fix is to swap over the entire hood.