89 YJ Engine Swap to a 89 4.0L from a Cherokee

[Josepkelk]

Hello All,

I'm a new user and have an 89 YJ with the 4.2L that has 109,000 miles on it and it runs like pretty bad. I put a Weber carb on it and still does not run well when I’m at altitude hunting and gets bad gas mileage. I'm thinking of doing the swap out with a 4.0L I can get an 89 Cherokee cheap with the 4.0L fuel injected with the transmission and transfer case. My question is can I pull the motor, transmission and transfer case out of the Cherokee and put them in my YJ?
I will need to change the CPU, fuel lines, fuel pump and wiring harness also? Will this swap be easier then putting in a 92 or newer motor that has a little more horse power or is it the same?

Any help would be appreciated.

Thanks

 

[yjdave]

First off sell that weber and get a ford 2100 carb. If you still want a 4.0L it's not a hard swap(not easy either) If you have a ax-15 transmission and 231 T/C that are in good shape then keep those and just get the newest 4.0L you can afford. You may need to switch the bellhousing for the cp sensor and still get all the above stuff switched over. Plus the intake on the newer one's is much better then the older renix one's. You will be happy with the increase in HP/gas mileage over the 4.2. I did a similar swap but with a 98' motor and transmission, just get as much from the donor rig/engine as possible.

 

[Josepkelk]

Thanks,
Is the motor, transfer case and transmission the same length in the Cherokee or are they longer than an YJ? Meaning are they the same or did they use different T-cases and Trany's in Cherokee's

 

[yjdave]

If the xj has a 5sp then it is the same length as what you have. If it is a auto then NO, it is probably longer if it is the 4sp auto. If it is the 3sp TF999 then the auto is about 1 1/2" shorter then a ax-15. Plus the XJ's use a 4sp auto that uses a stand alone computer that likes to go out(we'll just say the kinda stink and are expensive to fix). Are trying to keep a 5sp or go with a auto?

 

[Josepkelk]

I have a manual 5 and the donor is also a manual 5. I would like to buy this donor vehicle and just pull the works out of it and install it in my YJ. If I us the donor transmission that has the crank sensor in it this should save me some money?

 

[yjdave]

Sounds like it would work. I'm basically doing the same thing on a buddys 88 yj tomorrow. He got a 95 4.0 and were going to keep his transmission and t/c.
Almost forgot, you will need a wiring harness and computer from a 91-95 YJ. The xj wont work unless you really like cutting wire and forget it if the xj has the stupid anti-theft thingy.......good luck you'll be happy when it's al done....Just noticed your in the 'couv..small world might have to go wheeln' when you get it fixed.

 

[Josepkelk]

Thanks I saw that also we are neighbors. I can get the whole XJ so can I use its wiring harness? Or would it be easier for me to go to the junk yard and go with the 91-95 harness.

Thanks for all your help.

 

[yjdave]

The XJ is totally different and goes in threw the fire wall on the other side. Personally i'd go get a YJ one. Check ebay or maybe craigs list. The basterds over on foster are smok'n crack for theres $$$$. Plus you still have to rewire the plug to adapt to your fuse block.(about 1/2 dozen wires)

 

[Josepkelk]

The local junk yards are charging an arm and a leg for anything to do with Jeeps. Thanks I think I will pick up the XJ and get a harness and say goodbye to my 4.2.

Thanks