Help, Jeep XJ Engine Swap

Hello, i am currently driving a 1991 cherokee with a inline 6, 4L, auto transmission with about 275,000 km on it. Due to the previous owners mistake- not changing the oil for a couple years the engines life is at its last moments. Im thinking and been looking around for a new engine to put into the jeep. after calling around to a couple of places i got a couple solutions. one of which is a 1999 inline 6 4L, auto trans out of a grand cherokee with 112,000 km on it. Now, my question is, would that engine fit into my jeep and/or what kind of mods would i have to do to make it work. If the 1999 isnt an option what other years should i consider apart from a 1991 (as they are almost impossible to find with decent mileage). Thank you for your time.

-Mike  

That engine should fit just fine, modifications should be minor.  Just be prepared to work through issues as the raise their ugly head.

Other options are modern V6 and V8 GM engines.  Yes, a V8 does fit, I have one in my 1992 XJ.  A Vortec 4.3L GM engine would be better then any 4.0, but you'll need the engine, trans and a wire harness to get it to work.

If your short on cash, stick with a stock engine or get a rebuilt unit with a warrenty and don't sweat the fitment issues.  

If you wanted the '99 block and head and were planning on switching everything over from your '91, including the intake, all sensors, and all front drive accessories, then it might work.

Beware that the block changed in '96 and then again in 2000. A 2000 block is totally different with regard to accessory mounts and the water pump and will not work. The power steering setup changed in '95 along with a corresponding intake manifold change.

The accessories and brackets are different, some of the sensors are different, and the fuel injectors changed and fuel pressure changed from 39 psi to 49 psi in '96. The fuel pressure regulator is on the pump in the tank.

I you want the sure thing and the easiest swap, stick with '91-'95.  

If you have the funds i would just billed the motor you got if you have the skills do it your self or take it to a shop weather u pull it and that it to someone or get a remen your looking at 1,200 to 2,000 just a geass of what it would cost.