2.5 to 4.0 Q's

[Mud zjerk]

Well just got a layoff from work, so I have some time on my hands.
Just got a wrecked '98 4.0 auto from my aunt with 88,000 on it. I have a pretty clean '99 2.5 2dr with a 5 speed, but the little 2.5 has seen better days. I have all or most of the stuff I'm gonna need, so i'm gonna swap them.
On the later models is this a pretty straight forward swap? I'm no newb, I've built quite a few different rigs and cars, just looking for a little heads up if anyone knows what headaches I my run into. Am I going to need to swap the whole harness over? Will i need to cut off the frame mounts and get new ones? That's the kind of stuff i need to know. I do want to switch it to an auto so my wife and kid can drive and wheel it. They got pissed when I said I was gonna keep it a stick. Don't really have the $ to buy a ax-15 right now anyhow.
Thanks in advance.

 

[Mr_Random]

Well just got a layoff from work, so I have some time on my hands.
Just got a wrecked '98 4.0 auto from my aunt with 88,000 on it. I have a pretty clean '99 2.5 2dr with a 5 speed, but the little 2.5 has seen better days. I have all or most of the stuff I'm gonna need, so i'm gonna swap them.
On the later models is this a pretty straight forward swap? I'm no newb, I've built quite a few different rigs and cars, just looking for a little heads up if anyone knows what headaches I my run into. Am I going to need to swap the whole harness over? Will i need to cut off the frame mounts and get new ones? That's the kind of stuff i need to know. I do want to switch it to an auto so my wife and kid can drive and wheel it. They got pissed when I said I was gonna keep it a stick. Don't really have the $ to buy a ax-15 right now anyhow.
Thanks in advance.

PSHHH, they should learn stick... I learned at 15!

But anyways... fairly straightforward on later models. Whole engine harness from a 98 or 99 will be required, find an additional electric fan and a controller, swap the 2.5 accessory brackets over to the 4.0, and I'm fairly certain the mounts are the same... if not I doubt they will be hard to move. Make sure you have the tranny kickdown cable and such. Will a t-case be included with the 4.0/auto? I kinda doubt the 2.5's 231 will mate up to the aw4.

Oh, and driveshafts... the aw4 is longer, so the rear will be shorter and the front will be longer. Good time to get an SYE? haha.

I'll consult my FSM's if you need anything else

 

[Slip Kid]

The firewall will need to be modified for the 4.0 to fit.

 

[Mud zjerk]

I learned a stick at 15 also. Tried teaching my wife and kid on my xj and a few of my mustangs I've had. They just can't get it. Don't know if it's because they are lefty's or sumthin' but wife smoke'd my centerforce in my old 347 notch back I had. That was enough for me... She can have an auto.
The '98 4.0 is complete so i'll have the d/s's, tranny, t/c, and kickdown, all that stuff. I think I will ditch the clutch fan and go duals, like that Idea.
I thought the older xj/mj's had a different firewall and the later models were the same? Doesn't matter, I have a large selection of BFH's....

 

[PhotographerMike]

Just look at them side by side and you'll see whats needs to be swapped. If your aunts was wrecked in the front you might have some problems because I'm pretty sure that the header panel that the radiator is bolted to is further forward on the 6 cyl. and will need t be swapped. Plan on pulling the grill and radiator when you do the swap and you'll be fine. I'm sure all the mounting bolt holes for both engines / trans are the same in both frames. Put in new motor and trans mounts while you have it apart.

If you will be installing taller tires you MAY already have 4.11 gears in the 4 cyl. / 5 speed axles, that could save you a few hundred $$'s. IF you keep the 4 cyl. axles check your speedometer gear in the trans.

Good luck!

 

[alfman]

X's 2. When the engine bays are empty compare the firewalls. If there are any differences you will be able to see what needs to be moved around.

 

[lawsoncl]

The firewall will need to be modified for the 4.0 to fit.

Why? It's not like they made two different bodies. On the pre 87 (?) swapping in a 4.0 was an issue becasue that year never came with it.

 

[Mud zjerk]

I have heard form a few people that the older xj's had a different rad support and firewall. They also said they changed that in the later models?
It does have the 4.10's. I figure it will make a decent ride with some 31x10.5's and the auto. I also have most of a S35 kit for the rear, so that will help the tury-5 stay together for a while. will need to find another arb or ox cuz i sold the one I had.
This jeep I have is super clean-0 rust and the black paint is even still real nice. Only bad thing about the body is a bunch of little door dings all over. That's why I think the swap is worth while.
Just picked up an new set of HD leaves a buddy had layin around, and a RE 2.5" long aal to put in it. Still had a set of low mile ZJ u.c. v8 front coils. Shouls make for a decent lift. Oh and I bought all 4 spicer ball joints to put in it also. Wish I would have kept the ZJ v8 steering I had.
Should be a good starter rig for my kid!

 

[lawsoncl]

I have heard form a few people that the older xj's had a different rad support and firewall. They also said they changed that in the later models?

Yup. They changed when the introduced the 4.0 engine. 4.10's and 31s should be a good combo.