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89YJ AX-5 or AX-15

1510 Views 4 Replies 0 Participants Last post by  **DONOTDELETE**

I have a 89yj, I'm looking to do a engine swap. I have a I4 2.5L and want to but in a I6 4.2L (258). It looks like the front and rear ends will be fine, but how do I find out what Transmission I have, and will it work on the inline six. Does the six fix on the AX-5 or the AX-15? Thanks

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Dave, can't tell you for sure what tranny you have, but i can help you figure it out... there's actually three possibilities: AX5, BA10 and AX15. Easiest, but not definite is to determine when your vehicle was built, after June 89 Jeep used the AX15. Check your drivers door for a build date.

I crawled around quite a bit looking for the identification numbers as noted in the dealer service manual (good item to get if you don't have it, beats the chiltons manuals). If you can't find the id plates (which tell you exactly which tranny you have) then look for the tranny setup by first finding the drain plug. If the drain plug is immediately in front of the intermediate plate on the passenger side you've figured out you have a AX5 or AX15. Here's where the build date will help you 'guesstamate' - early build = AX5; June or after = AX15. The id tags for both are almost directly below the drain plug. If the plug is on the drivers side you've got the puegot ba10 (the id tag should be a few inches behind the plug towards the vehicle rear). Find that ID TAG to be absolutely sure - I'm just a hack at all this stuff and just went thru the same identification difficulties you are and found out I've got the ax15. Good Luck!

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I'm not sure of the reasons of why you want to swap in the 258 4.2, but that engine has caused many headaches for owners of Jeeps with that setup. The Carter carb is very tempermental and with all the vacumm lines it can be a real headache. You may want to consider a 4.0 swap if you want to stay with a 6 cylinder Jeep engine. Or depending on your needs go for a Chevy 350, lots of them around and parts are plentiful.

Just remember that every modification usually has a domino effect on other components and hence empties your wallet. Map all possibilities of where your decisions will take you.

Do not follow my Philosophy of Why do something once, when you can do it twice

Cutch 88YJ
The AX-15 is (was) only used in the six cylinder jeeps. You have the AX-5 or the Peugot (crap)--neither of which is strong enough for the six. I would also recommend going with the 4.0L H.O. engine over the 4.2. The 4.2 might have more torque, but it is just too temperamental and the 4.0 has plenty of power.

Got to agree the 4.2(had one in my YJ) is junk and I tossed mine for a Chevy 350...well worth the $$$$

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