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  #1  
Old October 4th, 2019, 22:49
Pgw1995 Pgw1995 is offline
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4.0 engine

Hey guys, I was wondering how hard it would be to install a 2004 Grand Cherokee 4.0 into my XJ. I just had a 04 Grand Cherokee engine rebuilt and now that I have decided to forgo the Grand build I am wanting to install the motor in my XJ. I know the motor mounts are different but luckily I work in a machine shop so fabricating mounts is not an issue, I have made many. I will only be using the block. This motor does have a Tupy head but I have a 7120 and want to keep it. The only thing I plan to use is the block and the newer intake manifold. What issues will I come across. I have put many non Jeep engines into Jeeps, those where complete engines though, not parts of engines miss matched, rebuilt entire Jeeps, and turned many wranglers into tube rigs. I can do the work, just pretty much need to know if anyone has knowledge of this swap and knows the mods that have to be done and whether it will even work without a total transformation and if my head will bolt to the block, if the newer style intake will bolt to my head, and if my tranny will bolt up? I have a 01 AW4. Thanks in advance!!
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  #2  
Old October 5th, 2019, 03:27
Jim Malcolm Jim Malcolm is offline
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Re: 4.0 engine

Use the XJ/AW4 flexplate; the WJ one doesn't cross over. CrPS, CaPS, CTS, ATS, IAC and coil rail are all the same. TPS is not.

The 7120 head will work just fine with the newer intake. Match the intake/exhaust gasket to the head. You really should keep the TUPY head for performance reasons but that's another conversation. The 0630/7120 head won't have the threaded hole in the front for the WJ idler pulley. You'll need to fabricate a way to support the coil rail or do the coil pack conversion.

The front accessories bolt on differently; the alternator is on top where the A/C compressor is on a XJ and the A/C compressor is on the opposite side of the motor beneath the PS pump. XJ accessories won't bolt onto a WJ block but mounts could be made with enough ingenuity. The alternator connector is different and obviously the AC lines are. Not sure how well WJ A/C lines will work on an 00-01 XJ.

You really should keep the WJ 4.0 all together, make mounts for it, swap flex plates, change the alternator connector, adapt the A/C lines or make it into an air compressor and drop it in. Much easier than trying to change the head or accessories.
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  #3  
Old October 5th, 2019, 06:48
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Tim_MN Tim_MN is offline
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Re: 4.0 engine

The simplest lowest cost solution is to sell what you have and buy what you need. All the fabrication for the motor mounts and the belt driven accessories brackets can be done, but if you ask me it is too much time/effort, and I work for a CNC fabrication and welding shop. Around here, a low mileage used 4.0L is $3-500.
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  #4  
Old October 5th, 2019, 16:37
Pgw1995 Pgw1995 is offline
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4.0 engine

Thanks guys. As far as the motor that is currently in my XJ, it runs fine other than it seems to have power loss. It doesnít use oil, I have done a complete tune up of everything without cracking the engine apart. I may see a great increase when I can finally back it out of my shop. I just did a complete upgrade from ground up. Tranny, transfer case, (I was just installing a SYE, but when I opened it, well I had to replace some things) installed 4:88 gears, paint inside and out. All started with just a transmission swap (PO installed a 91 transmission in my 98 Cherokee but kept the 98 TCM) took me till when I was going to replace a output speed sensor to finally figure that out. That was a costly experience. I just have the motor and thought I might as well keep it around because mine is pretty high on miles. Still havenít dug in to see how the PO made the 91 engine work out without throwing codes like the transmission did. I like it though, because of the head and I donít have a catalytic converter. On that subject, since I have just a straight exhaust with a high flow muffler, can I just remove the O2 sensors, still have the before and after cat sensors installed but I would think the readings would be relatively the same. But no, Iím not planning to install the engine soon but I know I will have to do something some day and itís there, already finished. 4.0ís here are $800-$1500 and $1200 to rebuild. I have already spent the money for the WJ rebuild. Now if I can sell it to rebuild my XJ 4.0 I will definitely. You


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  #5  
Old October 5th, 2019, 16:55
Pgw1995 Pgw1995 is offline
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Re: 4.0 engine

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Originally Posted by Pgw1995 View Post
Thanks guys. As far as the motor that is currently in my XJ, it runs fine other than it seems to have power loss. It doesnít use oil, I have done a complete tune up of everything without cracking the engine apart. I may see a great increase when I can finally back it out of my shop. I just did a complete upgrade from ground up. Tranny, transfer case, (I was just installing a SYE, but when I opened it, well I had to replace some things) installed 4:88 gears, paint inside and out. All started with just a transmission swap (PO installed a 91 transmission in my 98 Cherokee but kept the 98 TCM) took me till when I was going to replace a output speed sensor to finally figure that out. That was a costly experience. I just have the motor and thought I might as well keep it around because mine is pretty high on miles. Still havenít dug in to see how the PO made the 91 engine work out without throwing codes like the transmission did. I like it though, because of the head and I donít have a catalytic converter. On that subject, since I have just a straight exhaust with a high flow muffler, can I just remove the O2 sensors, still have the before and after cat sensors installed but I would think the readings would be relatively the same. But no, Iím not planning to install the engine soon but I know I will have to do something some day and itís there, already finished. 4.0ís here are $800-$1500 and $1200 to rebuild. I have already spent the money for the WJ rebuild. Now if I can sell it to rebuild my XJ 4.0 I will definitely. Jim, you said something about keeping the Tupy head for performance reasons? Why is that? I have been under the impression that the 7120 is the best head they ever made. I can not verify that, this is the first pretty much stock XJ I have ever had. Thank you guys for your input.


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  #6  
Old October 6th, 2019, 06:24
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Tim_MN Tim_MN is offline
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Re: 4.0 engine

Any 1990-2001 XJ Cherokee or 1993-98 ZJ Grand Cherokee 4.0 L engine block will interchange. As long as the right OBD-II parts are on the engine, the PCM doesn't care when the block was built.
*
Remove and re-use ( or replace with new ) as needed or required from your original engine: Intake/Exhaust manifolds, motor mounts, throttle body, fuel injector rail, flex plate/flywheel, cylinder head, water pump, distributor-less ignition or distributor assembly, OBD engine computer sensors, fan belt driven accessories, and/or mounting brackets.

I would not use the 0331 head unless it required for the PCM and emissions system being used. I would install a fresh cat and O2 sensors so everything runs correctly. If there is no O2 sensors the engine will likely run in Limp Mode and get crappy gas mpg's.
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Quote:
Originally Posted by bimmerjeeper

Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Quote:
Originally Posted by soyjer

Tim MAY be 100% correct, but why would a person automatically pick him as the expert .....
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  #7  
Old October 6th, 2019, 19:17
Pgw1995 Pgw1995 is offline
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4.0 engine

Tim_MN, the motor Iím referring to is a 04 WJ. My Jeep is a 98 XJ. Also, my XJ doesnít have a cat on it currently, so you are saying that I may be running in limp mode with my XJ and not throwing codes? If that is the case, then that may be why it doesnít have the power I think it should. I donít ever have any engine codes though. I know if I decide later to use the WJ motor Iíll have to use the cats. I have the hole rig so I can use everything out of the WJ, wiring harness, computer, whatever I need. Thanks


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  #8  
Old October 7th, 2019, 03:38
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Tim_MN Tim_MN is offline
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Re: 4.0 engine

Remove and re-use ( or replace with new ) as needed or required from your original engine: Intake/Exhaust manifolds, motor mounts, throttle body, fuel injector rail, flex plate/flywheel, cylinder head, water pump, distributor-less ignition or distributor assembly, OBD engine computer sensors, fan belt driven accessories, and/or mounting brackets.


The XJ PCM runs the instrument cluster, I doubt the WJ PCM is compatible or even speaks the same computer language as the XJ instruments. Don't make the a simple job harder thinking you will save a few bucks.
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Quote:
Originally Posted by bimmerjeeper

Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Quote:
Originally Posted by soyjer

Tim MAY be 100% correct, but why would a person automatically pick him as the expert .....
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