Engine Swap

[bluedragon436]

I have a friend that just picked up a 90 XJ. He drove it down to VA hours after purchasing and apparently it decided to blow up and now requires a new engine. I am just wanting to see if I can swap in an engine that is newer than the 90?? Like if say I can find a 95 or even a 97+ 4.0, will it swap in, with just changing out some sensors and such to the older 90 sensors?? Also was wondering if I swap in the newer exhaust, or at least the newer S-pipe will I be able to use the newer exhaust manifold?? I am pretty sure that I can pick up a 97 4.0 fairly cheap out of the JY that I know ran before it got taken to the JY, and am just trying to find out the feasibility of a swap/upgrade!! And I guess the only other issues I can think of, is the fuel system any different between the 90 and the 91+ year engines, like the lines that run up to the fuel rail and such, I know the fuel pressure is a bit different in the newer engines, but that can be taken care of by swapping the IM's..

[XJ Rat]

The block should work fine. But I believe the spline count on the crankshaft changed from the Renix to the HO (90 to 91).

[bluedragon436]

Oh crap... that's right... I forgot about the spline count.. So if I pick up the trans from the matching vehicle, I should be ok then.. then again I would need the TC too wouldn't I?? OH wait.. I won't matter between the engine/trans from the different years.. it would be the trans to transfer case spline count wouldn't it??

[uberxj92]

i work at the family machine shop rebuilding engines alot. the renix is as good as the HO engine. to tell you the truth it is easier & cheaper & less agrivating to just swap with another 89 or 90. or have that one you have rebuilt . just a thought

[bigjim350]

There are no splines between the motor and tranny. A 97 motor will bolt in fine.

[4.3LXJ]

Yes, a 97 will be just fine. Use the intake and sensors from the earlier and also the tstat housing from the earlier rig, unless you want to upgrade the cooling system.

[uberxj92]

Yes, a 97 will be just fine. Use the intake and sensors from the earlier and also the tstat housing from the earlier rig, unless you want to upgrade the cooling system.

you can use the tsat housing from the newer engine & put in a second temp gauge. can never have enough back ups LOL!
i upgraded the cooling system on my 90. its easy to do & seems to be easier to maintain.
my question is about the brackets for the peripherals aka alternator/ac? i have been told that the brackets change between over the years of the 4.0 life cycle. i know that the 2 alts & ac's are different between the renix & ho.

[XJ Rat]

Talk about a memory fart. The splines are on the other end.

[4.3LXJ]

you can use the tsat housing from the newer engine & put in a second temp gauge. can never have enough back ups LOL!
i upgraded the cooling system on my 90. its easy to do & seems to be easier to maintain.
my question is about the brackets for the peripherals aka alternator/ac? i have been told that the brackets change between over the years of the 4.0 life cycle. i know that the 2 alts & ac's are different between the renix & ho.

The brackets for the power steering should be the same, except again use the old intake. They did change AC pumps. So, again use your old brackets for this stuff.

[bluedragon436]

Well we found an engine that is newer than the 90.. so hopefully it won't be too much of a battle to install and get up and running.. after doing so probing with my hand randomly through the engine bay, found out he has a fist size hole in the side of the block, so rebuilding as a spare engine is def out on this one.. so no choice but to pick up another engine to drop in.. The only ones we could find were all 92+ and quite a few 97+XJ's.. The last one we talked to the yard about, and they said they'd be able to pull was out of a 92 Laredo w/ 5spd, now we shouldn't have any issues with just pulling the flywheel and such, and swapping on the flex plate, torque converter and bolting it up to the auto trans/bell housing correct?? Nothing special needs to be done to make this engine work with the auto trans with the exception of swapping everything over from the 90 engine to the 92 engine as far as the trans stuff.. Figure this will just be running as a newer version of the 90 engine by the time it is done and installed..