98 tj Motor swap

[Mitch984]

Hey I'm new on this forum so I don't know if anyone has posted anything like this yet so here it goes.

I have a 98 wrangler tj with the 2.5 with a 5 speed and the motor has high mileage and the syncros are about shot in the tranny so I am in the process of a motor swap. The donor is a 96 xj with the 4.0 ho and the ax15 5 speed I have the whole donor vehicle. Any info on the swap from motor mounts to wiring would be awesome. No I'm not doing a v8 swap and I'm not selling the jeep it's in way to good of shape body wise to do that

 

[GASnBRASS]

Motor mounts would have to be cut and rewelded into the correct position on the frame for the 4.0
Best to use the wiring and computer from the donor vehicle with the motor swap, and let it continue to think it's an XJ, but you might run into a few issues like evap monitoring or engine cooling fan (XJ uses electric cooling fan?). Not sure if the instrument clusters are fully compatible.

 

[Mitch984]

I've heard that the gauges probly wont work using the xj harness and computer but i may be able to get my hands on a computer and engine harness from a buddy that has a rotted out 4.0 wrangler. Would that cause too many issues? And how far do the mounts have to be moved I'm a little confused with that part because they came from the factory with either the 2.5 or 4.0 why would they give themselves the headache of having a different place to weld the motor mounts when they could mass produce the frames and just slap in whatever motor they were told goes in it

 

[GASnBRASS]

If you have access to a TJ wire harness and computer then definitely go with that. The motor mounts are in different places because the center point of the 6cyl and 4 cyl are different distances from the transmission. That's the only major frame difference I can think of from the factory between all the models. Couldn't tell you how far they have to move.

 

[Mitch984]

Thanks I got a chance to look at a wrangler with a 4.0 in it and the drivers side was clearly in a different place but the passenger side was almost the same spot

 

[Chris]

My understanding from what I read is that that engine will not fit in your TJ without some serious work. The wiring harness is entirely different, and there's a bunch of other stuff as well. However, if you have the entire donor vehicle, that makes thing much easier for sure.

Maybe someone will comment who has more knowledge on the matter, as I am just going off of internet "research" I've done in the past.

 

[Mike_H]

Isn't the transmission different between the 4 and 6 cylinder too? I don't know about physical size, but Pretty sure the 4 has a light duty transmission and the 6 has a medium duty (refering to torque rating). Your going to find that the bell housing and clutch are probably different as well.

 

[Mitch984]

I am getting rid of the ax5 that's in it because the syncros are shot and it won't work for the 4.0 anyway the donor jeep I have was a 5 speed had the ax15 so I have that part covered