flexin91xj

I have a '91 XJ with a AX15 and looking for a used motor to build up and swap in when the rebuild is over.
My question is, do I have to find another donor motor from the exact same year as mine? And, does the donor motor have to have had the same kind of trany mine does which is a 5 speed.
Any help would be great
Jeff

DFlintstone

I'm just learning here, but I think I can pass on a few things. So long as your PCM, TCU, and trans all stay a match, I would think any OBD-I 91>95 ought to work. NOT SURE! One question right away for me, if your temp. sensor for the gauge/light is at the rear of the head, that might have changed. I've seen that with a <90 Renix to newer HO heads, people have drilled & tapped to mount the rear head temp sensor. So if your 91 has it you may fit a 95 if it doesn't that way. I know people needing a TPS for a manual are advised to by the one for an auto cuz they are allot cheaper, (you just don't use the trans side of it if you have a manual). So if you use the TPS from an a replacement with an auto it should work. Just my 2 cents! I might search that some myself.

cruiser54

You've got a ton of choices. Easily anything 91 to 96 is a shoe-in. Others may require some mods but they're simple and many of us have done them. Trans is not an issue.

builtnotbought89'

Anything older than '95 will work without issue. Off its from a auto XJ the pilot bearing hole in the back of the crank won't have a bearing. Manuals came with 2 options for the bearings a large bearing, & small. Correct me if I'm wrong, but the pilot hole is the same for all 3 options. With the large bearing its just pressed into the pilot hole. The small bearing has a large race (that's won't come out in one piece! Lol) for the small bearing to set inside of. Either way the bearings should be readily available, & the pilot bearing race could be found from the dealer. You might want to check into the availability of those before starting the swap! Good luck

DFlintstone

Oh yea... pilot bearing. Having them fit in the first place might be nice. Thought I saw posted that that rear sensor lasted alittle past Renix, solvable anyway it looks.

flexin91xj

So my best bet would be an engine that origanally had an AX-15 hooked up from '91 through '95?

cruiser54

No. Trans is not an issue. Don't get off on that tangent.

DFlintstone

What I meant with, "Having them fit in the first place might be nice", computers and sensors aside, just plain being able to install the engine, "might be nice". I was being fasicious. It would be more than nice, essential!

So no, ether manual or automatic. I believe with built, there aught to be a bearing or bushing for it. I'm just curious myself if your 91 has a little sensor at the back of your head on the drivers side with one wire going to it.

Sounds like ether way with ether you are good to go.


^ Hi there Pete, we where typing at the same time!^

flexin91xj

So any 4.0 engine from '91 - '95 will work? No matter what?
Im going to spend a good amount of money on a used engine. And alot more money rebuilding it/stroking it and I just wanna make sure its right. Im on a very tight budget
I know I could throw any 4.0 in as long as I have the time and money to make it work. But I wanna go the simple route and make this swap as plug and play friendly as much as I can

Thanks for all the help guys!!!
And yes, my temps sensor is behind the head near the firewall. I changed it out when I dumped my idiot light cluter to one that actually has gauges.

DFlintstone

And yes, my temps sensor is behind the head near the firewall.
.................................^................ .............^ Thanks!

I've never done it myself. Cruiser is pretty much always on the mark, I think he left the Jeep dealership in the early 90's.

cruiser54

The 7120 head has the hole in it for the temp sender, which I believe is through 1995.

I've put 2 HO engines of the 92 vintage into Renix Jeeps with no problems. They had the temp sender hole.

flexin91xj

What about swaping in a 242 t-case in place of my 231. I know the 242 I will get has to have the same input spline count as what I have now ('91 AX-15 will have 23 spline I think...) but should I get a t-case thats in a 91-95 cherokee with a 5-speed? Or does it matter what tranny it had as long as the input spline count is the same? I know the newer cherokees have a different speedo input.