2.5-4.0 swap.

[89comanchesleeper]

i have a 89 2.5 swb with a 5 speed. not sure what tranny it is. my brother in law has a mj lwb 4.0 with a bad tranny. i might have a chance to buy his manchie. i was wonderin what all i would have to do to put his 4.0 in my truck. i really can't stand my 2.5. i wanted to put a 327 sbc in there but it sounds like a hassle and i know the 4.0 would push my swb manchie prudy good. and also would my tranny bolt up to that 4.0? any advise or tips would be great thanks

[mythreesons]

I'm a little confused...... You stated that your MJ has a 2.5 with a 5 speed but you don't know what tranny it is yet your signature states you have a 89 2.5 with a AX-5. Not enough Pepsi today??? :D

 

As for the important stuff..... Your BIL's 4.0 engine will go into your truck. Your tranny will not bolt up to the 4.0.

 

What is wrong with his transmission? Why not fix it and have two MJs?

 

Scott

[89comanchesleeper]

i was told mine had a ax-5. not sure if theres any other 5 speeds. and his tranny got stuck in rev one day and I'm to tranny doc so it would be easyer to just swap a new one in it when i put the motor in my truck. and his truck has been sittin for a while and is in pretty bad shape but the 4.0 still fires up like its cool.

[mythreesons]

Let's see if I get this straight........ If not, I'm sure someone will correct me. :D

 

The only manual trannys for the 2.5L were the AX-4 and the AX-5. The only difference was the added 5th gear in the AX-5. It will not bolt up the the 4.0L engine.

 

The only trannys offered for the 4.0L engine were the AW-4 (automatic w/overdrive), the BA-10 XXX 5 speed manual and later the AX-15 5 speed manual. The AW-4 is a decent tranny, but it is automatic. The BA-10, commonly referred to as the pukegoat, was phased out and replaced with the usually preferred AX-15.

 

For your situation, if you swap in a 4.0L engine, you will need a few extra parts from the donor vehicle to complete your swap. Basically, you take all the insides from the donor vehicle that relate to the operation plus a couple of new parts.

 

There are LOTS of write-ups in the DIY section that will help you to see the road ahead. I still haven't read all of them myself. Also, Pete has worked on the search engine some lately so it works a little better. If you limit searches to one forum, like Tech forum only, you'll have a bunch of info to read. Hint: search doesn't like AX-15 but it does like AX15, so try different combinations if one term doesn't work.

 

I guess the question I still have is why not buy the BIL's MJ, fix the tranny or replace it and have two trucks? You would end up on the good side of the situation.

 

Scott

[jteckmann]

That's also my understanding - If you want to replace the 2.5 with the 4.0, you need to use the 4.0's tranny as well. So you'll either need to get your brother's fixed, or find a working used one at the junkyard. From that point, the swap is pretty straightforward, and if you have both vehicles, you should have most the parts you'll need.

 

Either way, you'll have to address the tranny for the 4.0. So it's your choice if you want to have one nice truck with a 4.0, or if you want a nice 2.5 and a beater 4.0 to drive. :cheers:

[89comanchesleeper]

thanks for all the info. as for fixin my bil's truck. lol he beat it up pretty good and isnt nearly in as good of shape as mine. but the motor runs like a champ. I'm still tossin around ideas of what to do. i want to keep my truck a two wheel drive but make it fun to drive. hard to do with the 2,5. i could strip the other truck for a lot of things but its still beat up pretty bad.

i love to go 4wheelin. but i also love to go fast in a sraight line. oh i put a mild tune up on the pile of 2.5 today. i.e plugs cap rotor. and the danr thing started missin and buckin. :mad: :mad: it seamed to slowly ease off with the spitin as i drove it around. i guess its anouther jeep thing we love so much!! :nuts:

 

 

 

nothin a tourch and duck tape won't fix