'91 XJ 4.0 in a '94 YJ

[deerej4840@yahoo.com]

I have a 4.0 that came out of a '91 XJ that was wrecked. It has an automatic transmission also. I want to put it in my '94 YJ that has a 2.5 in it. Is this a possible swap and if so what will I need to do for the change over?

 

[jps4jeep]

Yes very possible, will be cheaper to sell the motor, and the jeep and just buy one with a 4.0 in it.

If your really attatched to that YJ, look to swap something else in that will be a little easier on you and your wallet like a small block gm motor.

 

[deerej4840@yahoo.com]

So I guess it is not just a bolt in and go...

 

[Bounty__Hunter]

Far from a bolt-in, not as simple as most think. For starters you need to cut the motor mount perches from the frame and fab/weld on new ones. In the end you spend a lot of $$ and time to only have another run of the mill 4.0L jeep with a hacked up install.

Look for a GM 4.3L or v8 drivetrain as companies like Advance Adapters and Novak make great bolt-in motor mounts for your jeep. Get the GM transmission and transfer case with the engine so you save huge $$ on adapters.

 

[jps4jeep]

If you go with a GM, yous a GM transmission, But the np231 was used widely through out the GM mid size truck line, so adapting it to a say 4L60e transmission (most 1/4 and 1/2 tons gm) is as simple as swapping a main shaft (if needed) and bolting up. and still retaining your original T case.

swapping a main shaft in a tcase is 9999 times easier than swapping a Transmission main shaft.

 

[Bounty__Hunter]

If you go with a GM, yous a GM transmission, But the np231 was used widely through out the GM mid size truck line, so adapting it to a say 4L60e transmission (most 1/4 and 1/2 tons gm) is as simple as swapping a main shaft (if needed) and bolting up. and still retaining your original T case..

Can't be done, the front case half is different between the two. The 231C uses a 5-bolt pattern to attach to the transmission and the 231J is a 6-bolt pattern. Best to source the GM drivetrain complete from engine to transfer case.

 

[jps4jeep]

oh snap. you are correct. Brain farts will get the better of you now and then.

Can you swap front cases?

 

[Bounty__Hunter]

Yes, front and rear case halves will interchange, but the 231C uses a really long mainshaft and longer tailhousing, so it's best only used with a SYE. An advantage of the 231C is it usually has a 4 or 6 gear planetary, stronger than the 231J's standard 3 gear.

 

[Boze]

I was actually thinking of this today. My 4.0 has 180,000 miles on it and I was thinking of the cheapest way to swap it out. It's pretty much inarguable that the good 'ol Chevy 350/TH 350 combo has the best bang:buck ratio of any motor ever, as most people only have to ask around and someone WILL know someone who's cousin is giving one away. But I grew up with full sized Chevs and muscle cars...it just seems like a long combination, (esp with the T-case), to fit in a Wrangler. You say Adv. Add. makes a kit to just bolt a small block bowtie in there? The 4.3 I can see, but a small block must need some sawzall work.

 

[deerej4840@yahoo.com]

well I was just wondering, I have the motor sitting there and if it would be easy I was going to put it in. Will it bolt up to the ax5 transmission without any mods? I know I would have to change the flexplate out for a flywheel.

 

[Bounty__Hunter]

There's plenty of room in a YJ for a 350 without any cutting. Hell, you could fit a bigblock in there.

Nothing will bolt to the AX5 but the 4cyl, and you wouldn't want to put any more power to that little transmission.

 

[Drdan524]

I am currently in the process of swapping a 4.0L stroked into my 89 YJ and I am down maybe $50 so far after I bought the 1999+ intake manifold, bearings and pistons. I bought a donor 1992 Xj and I am swapping the complete drivetrain over. I am rebuilding the 4.0L and making it a 4.6L. The swap is more labor intensive than anything else with the wiring being the most difficult. But if you look around all the Jeep forums online you can find all you need. I will probably spend about $500 total at the end of the swap.

Thanks,
Dan