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Unread 09-12-2012, 12:19 PM   #1
OKwranglerYJ
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Help with 4.0 swap

Ok I have a few questions that I couldn't find the exact answer to. I also want to use this thread as my question thread. I have a 95 Rio Grande and I want more power so I researched for about 6 months and decided that the 4.0 was MY best bet and I just so happened to get auto 95 Cherokee for $500 so why not.
Question 1: Will my engine brackets (the ones that bolt to the engine)I have between the YJ and Cherokee work for the swap.

Question 2: Can I cut the frame mounts and just move them or do I need new ones.

Question 3: What computer do I need because I found some that said it would work for auto or standard.

Question 4: What transmission mount and bracket do I use because I found some that said it would work for ax5 and ax15

Question 5: What sensors do I keep and which ones do I switch.

Now I have read almost every thread I could find on google I just want a thread to call my own for my reference. I will have more questions later it that all I can think I for now. Thank you in advanced.

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Unread 09-12-2012, 02:14 PM   #2
Que89YJ
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Hey OK. You havent posted in a while. If you are swapping try and get all the sensors with the new one. Most will cross over. The ecu will work from any auto/manual 91-95 xj/yj.
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Unread 09-12-2012, 02:44 PM   #3
remmons
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Quote:
Originally Posted by OKwranglerYJ View Post
Ok I have a few questions that I couldn't find the exact answer to. I also want to use this thread as my question thread. I have a 95 Rio Grande and I want more power so I researched for about 6 months and decided that the 4.0 was MY best bet and I just so happened to get auto 95 Cherokee for $500 so why not.
Question 1: Will my engine brackets (the ones that bolt to the engine)I have between the YJ and Cherokee work for the swap.

Question 2: Can I cut the frame mounts and just move them or do I need new ones.

Question 3: What computer do I need because I found some that said it would work for auto or standard.

Question 4: What transmission mount and bracket do I use because I found some that said it would work for ax5 and ax15

Question 5: What sensors do I keep and which ones do I switch.

Now I have read almost every thread I could find on google I just want a thread to call my own for my reference. I will have more questions later it that all I can think I for now. Thank you in advanced.
There are quite a few threads on the JF board that go into this particular swap. I have used several of them to complete my swap. If you see any posts or replies from que89yj, tshark299, or from cevans87yj, you can always count on their advice, these two guys are solid. I would have been lost (or just took a little longer) without them.
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Last edited by remmons; 09-12-2012 at 02:45 PM.. Reason: Added info.
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Unread 09-12-2012, 09:47 PM   #4
OKwranglerYJ
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Well thanks Que you made my day and saves me some money. I had no idea jeep computers were so expensive. 2 questions down only a few more to go
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Unread 09-13-2012, 01:42 AM   #5
Michaelgoesrawr
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Quote:
Originally Posted by OKwranglerYJ
Well thanks Que you made my day and saves me some money. I had no idea jeep computers were so expensive. 2 questions down only a few more to go
If you think you can cut the frame mounts off and re use them where they need to be then you can do that. If you botch it you'll have to make new or find some.

And the motor mounts are probably the same, but I'd get new while you're in there. I do not know that forsure though.
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Unread 09-13-2012, 06:38 AM   #6
Que89YJ
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Those mounts are hard to buy. You need to try and cut and reweld them. Yes you can reuse the frame mounts. The engine mounts are different if I remember correctly. One side is a little taller then the other.
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Unread 09-13-2012, 06:17 PM   #7
OKwranglerYJ
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Ok I need to get my terminology correct. I'll call the one that bolts to the engine the engine bracket then the motor mount them the frame bracket. Can I reuse the engine brackets.
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Unread 09-13-2012, 06:38 PM   #8
jonzjeepyj
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No one side is different. I went to the local U pull it yard and found several sets left in the motor mounts after the motors were pulled. I ended up buying a set for 20.00 bucks.
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Unread 09-13-2012, 06:49 PM   #9
OKwranglerYJ
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Now all I need to know is if the transmission mount and bracket will work.
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Unread 09-13-2012, 11:28 PM   #10
Leans93
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Question 1: Will my engine brackets (the ones that bolt to the engine)I have between the YJ and Cherokee work for the swap.

The 2.5L engine brackets won't work. The XJ and YJ 4.0L brackets on the passenger side are identical. The drivers side however are different. Though they look the same the bolt hole is moved an inch or so closer to the engine and it won't work. I've tried. You will need the bracket from a 4.0 YJ. As stated junkyards or eBay will have them or you can buy from Browndog.

Question 2: Can I cut the frame mounts and just move them or do I need new ones.

You can cut and move.

Question 3: What computer do I need because I found some that said it would work for auto or standard.

Auto, standard doesn't matter. Just get one from a 4.0. From what I understand XJ comp will work to but my experience is with a YJ comp. 91-95 will work.

Question 4: What transmission mount and bracket do I use because I found some that said it would work for ax5 and ax15

The metal brackets are different. the rubber mounts are the same.

Question 5: What sensors do I keep and which ones do I switch.

I used all the ones from the 4.0. I don't remember which ones interchange but you can look up parts on Oreilly's website and it will list compatibility.

If you haven't checked out this thread you might want to:
http://www.jeepforum.com/forum/f12/l...e-pics-668796/
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Unread 09-14-2012, 06:59 AM   #11
OKwranglerYJ
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Thanks lean and yes I have read your thread front to back. Some of the questions I kinda knew others I didn't. I'm glad you and Que chimed in, that's what I was going for. Also I was wondering how much did the swap help and what you would have done different.
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Unread 09-14-2012, 08:35 AM   #12
seraph_rapture
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I did the same swap, I might be able to answer a few things.

Wiring is the biggest headache I ran into. I ended up splicing the 4.0 harness into my 2.5 bulkhead and while it worked I still haven't gotten all the accessories hooked up. I heard tell that you can just add two wires for the extra injectors and re-use your old 2.5 harness, I'd look into that. There's a definite power increase in moving to the 4.0 but if I had it all to do over again I would have found a carbed 350 and swapped that in. In the end of it the 4.0 swap isn't any easier than swapping in a carbed V8 because of all the wiring and fabrication you have to do.

The other thing I would do differently is do one thing at a time. When I did the swap I originally planned to just swap the engine and transmission and be done with it. That in turn led to an 8.8 in the rear and 10" of lift. Finish the engine swap first and then worry about everything else later, once you have all the issues worked out.
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Unread 09-14-2012, 08:54 AM   #13
Que89YJ
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The wiring should only be adding the 2 additional injector wires and swapping the ecu. If you use the auto ecu on the manual you have to ground the nuetral saftey switch. The sensors themselves all swap over. The cam, crank, temp, oil pressure, mat, tps,the VSS are the same. Different distributor and IAC, and throttlebody. Alternator will work but the bracket is different so make sure you get the backet.
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Unread 09-16-2012, 08:47 AM   #14
OKwranglerYJ
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Quote:
Originally Posted by Leans93
Question 1: Will my engine brackets (the ones that bolt to the engine)I have between the YJ and Cherokee work for the swap.

The 2.5L engine brackets won't work. The XJ and YJ 4.0L brackets on the passenger side are identical. The drivers side however are different. Though they look the same the bolt hole is moved an inch or so closer to the engine and it won't work. I've tried. You will need the bracket from a 4.0 YJ. As stated junkyards or eBay will have them or you can buy from Browndog.
Well yesterday I worked a little on the engine and got to looking. To me it looks like they designed the driver side to be either Yj or Cherokee and they just drilled the hole in a different spot. So what would keep me from just drilling a new hole to fit where I need it.
image-1155400095.jpg   image-4032776187.jpg  
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Unread 09-16-2012, 12:34 PM   #15
chasmosis1
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Quote:
Originally Posted by OKwranglerYJ View Post
Well yesterday I worked a little on the engine and got to looking. To me it looks like they designed the driver side to be either Yj or Cherokee and they just drilled the hole in a different spot. So what would keep me from just drilling a new hole to fit where I need it.
I am currently on my 3rd swap and can give you some info on this subject.

I have redrilled the motor bracket and it will work just fine, though having the XJ hole in there makes it a little weaker.

Que89YJ is correct on the wiring. The easiest way is to cut open your 2.5 engine harness and add in the 2 sets of injector wires and plugs. You will need to reposition a few wires and extend a few as well due to the added length of the 4.0. The ECU (Computer) from the XJ will bolt right in and be plug and play. I do not recall having to short the neutral safety switch, I am thinking that your clutch safety switch replaces it, but I may be wrong on that.

Your sensors from the XJ or the 2.5 will work fine.

You will need some new brackets on the front of the motor to position everything correctly for the YJ. You can reuse the 2.5 upper alternator bracket that holds the A/C compressor as it is the same for the 4.0 YJ. You will need a lower alternator bracket that is YJ specific, and not very easy to find. You will also need to change the waterpump as well as your fan, fan clutch, and fan shroud with 4.0 YJ specific parts.

You did not specify what transmission you are going to use. You cannot use the AX5 behind the 4.0. If you plan to use the auto, than thats a whole new deal as you will need to re-clock the transfer case and fabricate a mounting spot in your crossmember/bellypan just for starters. If you have obtained an AX15, than you will need the steel transmission bracket that goes between the trans & rubber mount, as well as the bellhousing (the external slave cylinder type), flywheel, & clutch. You will also need the tcase for the AX15, or swap the input shaft out in your 2.5 tcase. The AX5 rubber mount is the same for the AX15.

Your driveshafts will need lengthened/shortened as well.

Though I have never reused the frame brackets for the 2.5 to the motor, I have seen many on here that have reused them successfully.
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Spare - 91 YJ Hardtop, 4.0, AX15, 4.10's, 4" lift - Currently under construction........
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