4.0 to 5.2 should I - JeepForum.com
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post #1 of 25 Old 04-11-2019, 09:03 PM Thread Starter
Ndheep
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4.0 to 5.2 should I

I have two 98's one with the 5.2 runs good but had body problems and electrical issues. Just bought the other 98 with the 4.0 in it. The trans lost reverse on the second day of owning it. I could take the parts I need off the 4.0 and put on the 5.2, but it is rusty. The 4.0 Jeep is in much better shape and doesn't have things I don't care for like a sunroof.

The brown one is the 4.0 and the primer gray is the 5.2.

Motor swap or body swap?

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post #2 of 25 Old 04-11-2019, 09:13 PM Thread Starter
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Better pic of the 5.2
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post #3 of 25 Old 04-11-2019, 11:57 PM
Timo_90xj
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If you wanted to swap the 5.2 to the 4.0, you'd need to swap the engine, tranny, I'd highly suggest swapping axles as well (d44a rear and both axles having 3.73 instead of the 3.55s on the 4.0), you would need the PCM and most of the wire harness, etc.. and having electrical problems in the 5.2 it's likely those problems swap along with the engine/ tranny/ pcm/ wire harness.
Also keep in mind the 42RE behind the 4.0 does not share the same bellhousing and bolt pattern as the 44RE behind the 5.2 - 4.0 uses AMC and 5.2 is a Mopar.




Looking at the rust on the 5.2 rocker, I'm pretty sure that's just the easily visible part of the rust issues. It more than likely has enough underbody rust on the floor pans, uniframe rails, CA mounting brackets etc. that's it's not even worth fixing at that point. If it has severe rust at or near control arm mounting brackets, it is an actual safety hazard to drive it.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #4 of 25 Old 04-12-2019, 12:13 AM
IMMORTEN
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Correct me if I am wrong; but wouldn’t it be more feasible to sell off both of those and buy one good ZJ?

I mean I see decent running examples of ZJs for sale here in Denmark for €2500 - €4000

I can imagine (without having it confirmed) that you could get that if you sell both of those ZJs you have...maybe as parts if needed.

Just my input


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post #5 of 25 Old 04-12-2019, 07:41 AM Thread Starter
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The 5.2 is rusty. The doors are off a 94 gc it's kinda a pile. But it does have a rebuilt 5.2 and I swapped in a np 231.



I can't sell the 5.2, It"s title isn't clean. could sell as parts but won't get much for it. The 4.0 has a bad trans. Around here it won't get much either. I paid $500 with it running and driving.



I have a hp d30 to swap in and might just change the gears to 4.56 because i will need to re gear it anyways. The d44a will be swapped in also.


I have both so what ever needs to be swapped I have it or I will replace it with new. Most of the electrical problems are inside. Engine and trans work great
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98 Grand Cherokee limited 5.2 pos
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post #6 of 25 Old 04-12-2019, 08:29 AM
HighLonesome
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First, I would rectify the transmission problem in the 4.0 and have a running vehicle.
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post #7 of 25 Old 04-12-2019, 08:30 AM
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In addition to the above, I believe you would need to weld 5.2L frame-side motor mounts to the 4.0L's chassis.

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post #8 of 25 Old 04-12-2019, 08:53 AM Thread Starter
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The trans in the 4.0 lost reverse. It would need a full rebuild. Not willing to do that. Plus the motor has a knock to it.

The 5.2 runs and drives.

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post #9 of 25 Old 04-12-2019, 09:39 AM
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Quote:
Originally Posted by Ndheep View Post
The 5.2 is rusty. The doors are off a 94 gc it's kinda a pile. But it does have a rebuilt 5.2 and I swapped in a np 231.



I can't sell the 5.2, It"s title isn't clean. could sell as parts but won't get much for it. The 4.0 has a bad trans. Around here it won't get much either. I paid $500 with it running and driving.



I have a hp d30 to swap in and might just change the gears to 4.56 because i will need to re gear it anyways. The d44a will be swapped in also.


I have both so what ever needs to be swapped I have it or I will replace it with new. Most of the electrical problems are inside. Engine and trans work great



Ah I see, thank you for clarifying that


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post #10 of 25 Old 04-12-2019, 09:42 AM
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4.0 to 5.2 should I

Quote:
Originally Posted by Ndheep View Post
The trans in the 4.0 lost reverse. It would need a full rebuild. Not willing to do that. Plus the motor has a knock to it.

The 5.2 runs and drives.

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Is it expensive / feasible to pull a 4.0 transmission out of a wreckers yard?

My 4.0 has kind of a knock to it as well, mainly when cold, I think it just needs a good service, I’m having it in for service on Monday anyway


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post #11 of 25 Old 04-12-2019, 09:54 AM Thread Starter
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I'm going to use the 5.2 no matter what. It is a motor swap or I part out the 4.0

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post #12 of 25 Old 04-12-2019, 11:01 AM
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From what I understand, the knock on initial startup in the 4.0 is usually just piston slap and is not a huge problem.

It seems like you've decided what you want to do, and it seems like you want to take on the project of putting the 5.2/44RE behind the body of your 4.0, and whatever axles and other mounting work comes along with it.

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post #13 of 25 Old 04-12-2019, 11:04 AM
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Quote:
Originally Posted by CatSplat View Post
In addition to the above, I believe you would need to weld 5.2L frame-side motor mounts to the 4.0L's chassis.
Mounts bolt on, but yeah, you gotta swap to the 5.2 frame mounts.

If you've got a lot of free time, then 4.0 shell looks to be in better condition. It's not a quick swap, but you've got all the parts you need to make it work.

We can't really tell you what your time is worth. You gotta decide what you want to come out with and how to get there.


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post #14 of 25 Old 04-12-2019, 11:05 AM
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Quote:
Originally Posted by Ndheep View Post
I'm going to use the 5.2 no matter what. It is a motor swap or I part out the 4.0

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Okidoki then

Will you keep us posted on the swap?

Would be interesting to see


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post #15 of 25 Old 04-12-2019, 11:11 AM
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Quote:
Originally Posted by Ndheep View Post
The trans in the 4.0 lost reverse. It would need a full rebuild. Not willing to do that. Plus the motor has a knock to it.

The 5.2 runs and drives.

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Just because it lost reverse doesn’t necessarily mean it needs a full rebuild even though most if not all trans shops will recommend that.

Will a full rebuild fix the problem? Of course, but it could be a rather minor issue fixed by replacing the electronics doing multiuple fluid changes and adjusting the bands.

I don’t think anyone has mentioned that most of the A/C components are on the opposite side of the engine in a 5.2 ZJ. There are so many other little things that you will need to change that make it not practical.

Even if you need a full rebuild it will be cheaper and quicker than attempting to swap a 5.2 in a 4.0 shell

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