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Unread 12-19-2014, 07:55 PM   #1
Paxter
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question regarding 4.0 swap into a 2.5l TJ

Im getting close to swapping my 4.0 into my 99 2.5L TJ and I had a question. Since both jeeps are manuals and only a year apart, would I be able to swap just the engine instead of the whole driveline? My 4.0 is in my 2000 TJ and the 2.5L is in my 99.

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Unread 12-19-2014, 09:07 PM   #2
samuraisavr
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Nope, 4.0 has a ax15 or nv3550 behind it as well as a np231 with a 23spline input shaft. Your 2.5 has a ax5 and a np231 with a 21 spline input shaft. Also, if your 4.0 is a 2000+ and your ECU is a 2000+ as well you'll have a communication problem. 97-99 used PCI and 2000 up uses CCD to communicate with the gauge cluster. There is a wealth of information on this site if you search for it. Lots have done it and some have contemplated it and decided otherwise. There are a lot of variables that will determine if the swap is worth it to YOU. In the end most will tell you that it is more cost effective to sell your tj and buy a 4.0 tj. However if you have a LOT of mods to your Jeep it may be worth your time to do the swap. I have a 03 with a 2.4 that is blown up and I am considering swapping a 4.0 because the 2.4s are ridiculously priced. However looking at what the 4.0 swap would cost, I have to consider other v8 swaps. Take this info for what you will. Good luck either way.
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Unread 12-19-2014, 09:53 PM   #3
Paxter
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Ouch..so my 4.0 won't even work anyway. I was also considering a v8 swap but have done zero research into that. Thanks for the info
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Unread 12-19-2014, 10:15 PM   #4
TripLeader
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I used to have a '00 with a 2.5L. I looked over the input of those much more mechanical than I, and came to the conclusion swapping to a 4.0L was not the route for me. I suggest selling and buying a Jeep with the motor you want in it. But if you swap, go V8 is the conventional wisdom.
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Unread 12-19-2014, 10:26 PM   #5
Paxter
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I bought this 2.5l because the previous owner already did everything that I ever wanted to do to a jeep...it's just the only downside is its a 2.5l. I think if anything I'll look into swapping to a v8 and selling parts from my wrecked 4.0 donor
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Unread 12-19-2014, 11:43 PM   #6
Paxter
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I apologize for asking a question thats probably been asked a ton..but for some reason I cant seem to find any when I search. So, Since I have a perfectly working 4.0L-NV3550-np231 in my wrecked Jeep, I can replace the whole driveline in my 99 2.5L with my donor 4.0? The only issue I will have is with my ECM? What if I used all the wiring from my 2000 4.0 a long with my gauge cluster?

In other words I have a fully functional 2000 4.0L thats mechanically sound (minus the body and rear end) that I can use as a donor.
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Unread 12-20-2014, 09:56 AM   #7
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Quote:
Originally Posted by Paxter View Post
I apologize for asking a question thats probably been asked a ton..but for some reason I cant seem to find any when I search. So, Since I have a perfectly working 4.0L-NV3550-np231 in my wrecked Jeep, I can replace the whole driveline in my 99 2.5L with my donor 4.0? The only issue I will have is with my ECM? What if I used all the wiring from my 2000 4.0 a long with my gauge cluster?

In other words I have a fully functional 2000 4.0L thats mechanically sound (minus the body and rear end) that I can use as a donor.
It will work fine. Just be patient and careful moving the harnesses over.

To clarify on your first question though, even if all the other stuff weren't true, the number one reason you couldn't easily just transplant the motor over is the bell housing pattern is entirely different.
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Unread 12-20-2014, 10:07 AM   #8
Paxter
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Originally Posted by mrblaine View Post

It will work fine. Just be patient and careful moving the harnesses over.

To clarify on your first question though, even if all the other stuff weren't true, the number one reason you couldn't easily just transplant the motor over is the bell housing pattern is entirely different.
Alright, thanks! I'll start on taking the engine out this next week
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Unread 12-24-2014, 11:13 AM   #9
joe_jeep
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Normally most of us would tell u to sell the 4cyl jeep, and buy a 6 cyl jeep.
Its just a better option for most people. Since u have a complete donor jeep, its makes it a ton easier.
Go for the swap. Good luck!
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Unread 12-24-2014, 05:56 PM   #10
Sudcalifornio
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i wish we can do engine swaps on jeeps in California, mine has the 2.4l engine
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Unread 12-24-2014, 06:05 PM   #11
sduncan
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Quote:
Originally Posted by Sudcalifornio View Post
i wish we can do engine swaps on jeeps in California, mine has the 2.4l engine
You can...just educate yourself on what is required.
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Unread 12-24-2014, 06:17 PM   #12
joe_jeep
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Or move a way from the liberals?
Im sure its beautiful though.
The cost and regulations would push me out.
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Unread 12-24-2014, 07:08 PM   #13
Sudcalifornio
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i wouldnt leave California, it has any everything the jeepers wanna be off roading (mud, desert, forest....)

i dont have the money, nor the knowledge in mechanicals, what can i say in legal (CARB, DMV) stuff.
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Unread 12-24-2014, 07:53 PM   #14
mrblaine
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Quote:
Originally Posted by Sudcalifornio View Post
i wouldnt leave California, it has any everything the jeepers wanna be off roading (mud, desert, forest....)

i dont have the money, nor the knowledge in mechanicals, what can i say in legal (CARB, DMV) stuff.
A swap from another TJ of the same year is as easy as doing the work and going to get it smogged as long as you carry over all of the emissions stuff.

A swap from another brand is also able to be done. The biggie is that it must be from the same year or newer and you attempt to maintain the OEM emissions for that motor.
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Unread 12-25-2014, 06:26 AM   #15
greenmachine99
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You won't have to swap your gauges over. Both your 99 and 2000 are ccd bus. Ccd bus was used 1997-2000, PCI bus was used 2001-2006 unlike stated earlier.
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