Hello All - I have a 97 2.5L wrangler with 90,000 miles. Unfortunately, my oil pressure has gone to crap and I’m in need of a new engine. I’m thinking about upgrading to a 4.0L and was curious as to how straightforward a swap would be. Will I need to worry about electric, transmission, mount etc… to perform the swap? My father in law has offered to install the engine (he owns his own automotive garage) but I have not approached him about the upgrade and want to get your thoughts before I do. Any input is appreciated. Thanks - Gio

The 4.0L will not bolt up to your existing transmission. If you plan to swap, get the entire drivetrain (motor, tranny, and t-case)from the donor vehicle. I wouldn't say it is difficult, but there are many small details. Do lots of research before deciding to go this route.

Thanks, I will definitely do research. It looks like I would need to address the following at the minimum to perform the swap.

1) Transmission and Transfer Case
2) Wiring Harness and Computer
3) Modify Motor Mount Brackets
4) Drive Shafts?
5) Radiator
6) Exhaust?

Yep, all of the above. Sounds like you understand the complexities, but does your mechanic. It won't be a 2 hour motor swap. If you can find a wrecked Jeep, and buy the whole thing cheap, that's your best bet.

before you assume that your motor is crap, why dont you get a compression test, a leak down, and maybe even buy yourself a new oil pressure sending unit from autozone for about 25.00. my oil pressure was dropping to about 8 pounds and i went and got a new sending unit and its back up to about 18 or so at idle. i dont blame ya for wanting a 4.0 or higher but check your 4banger before you retire it. that way you can save a lil more and it will afford you some more time to look and research.