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Unread 05-02-2011, 10:18 PM   #1
Lucanuss
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1994 YJ Wrangler 
 
Join Date: Apr 2011
Location: loveland, colorado
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YJ motor swap to a newer year!!

Hello!

I am in need of a new 4.0L block for my 94 YJ. I have found a few 98+ Wrangler/Cherokee used blocks that i can get cheap. My question is, Can I put all motor components onto a newer block with out problems. or what year did the 4.0 change to which it would not match up with YJ components?

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Unread 05-03-2011, 12:05 AM   #2
18Dmedic
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1989 YJ Wrangler 
 
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Location: Sacramento, CA
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I believe 87 to 90 are the same and 91 to 95. I believe that the 97-up are different.
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Unread 05-03-2011, 12:36 AM   #3
mike_breaker_5
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i think the main differences in tj 4.0's and yj 4.0's are the intake manifold and possibly the head. the reason there is no '96 wrangler is partially due to the addition of emissions testing to vehicles.

i know you can put a yj 4.0 into a 97 tj that had a 4.0 in it previously. i don't see why you can't go the other way and slap the newer motor in the yj, but the extent of the parts interchange is uncertain to me. like i said before i know the intake is slightly different due to emissions crap being added in the tj run, simply retain your intake and exhaust manifold. i think after that it's basically the same motor until i think 99 when they changed the head, but i bet the tj 4.0 head will still work if left on the tj motor, the computer won't know the difference.

if you can see the motors side by side out of the vehicle compare everything to see what's different, and just swap it over, i would do a forum search, there has to be someone here that has done it.
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Unread 05-03-2011, 09:08 AM   #4
Rynfw100
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1993 YJ Wrangler 
 
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Quote:
Originally Posted by mike_breaker_5 View Post
i think the main differences in tj 4.0's and yj 4.0's are the intake manifold and possibly the head. the reason there is no '96 wrangler is partially due to the addition of emissions testing to vehicles.

i know you can put a yj 4.0 into a 97 tj that had a 4.0 in it previously. i don't see why you can't go the other way and slap the newer motor in the yj, but the extent of the parts interchange is uncertain to me. like i said before i know the intake is slightly different due to emissions crap being added in the tj run, simply retain your intake and exhaust manifold. i think after that it's basically the same motor until i think 99 when they changed the head, but i bet the tj 4.0 head will still work if left on the tj motor, the computer won't know the difference.

if you can see the motors side by side out of the vehicle compare everything to see what's different, and just swap it over, i would do a forum search, there has to be someone here that has done it.
As the OP said, "BLOCKS" is what he's asking if he can interchange. I believe if you keep the top-end components from your YJ 4.0L and swap them to the TJ 4.0, it should work. If you keep the top end components, you have to switch the ECU, Wiring Harness, and get set up for OBD-II as well. But anyways, do your research, go to the FAQ, I believe I saw a couple of TJ to YJ swap write-ups.
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Unread 05-03-2011, 10:07 AM   #5
Alfons
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1992 YJ Wrangler 
 
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If you're asking about fitting an early TJ 4.0 into a YJ wiring and fuel environment, the answer is that you can do that. You need to find a spot for all your sensors, swap your throttle body, fuel rail and injectors. There are a few other odds & ends that you'll need to deal with, but it's all straight forward. You may need to swap the flywheel to match the Crank Sensor needs, but that's not hard to do - if you do need to change the flywheel, I believe the bolts are Torque To Yield (TTY) type & if so, you'll need a new set of bolts.
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