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Unread 08-27-2007, 02:42 PM   #1
gjohnson
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1986 CJ7 
 
Join Date: Jan 2003
Location: Fairfield, CT
Posts: 125
4.0L Engine Swap

When I was planning for this project I had a hard time finding information, so I figured one more thread wouldn’t hurt. This write-up involves the process of installing a 1994 4.0L Cherokee engine, AX-15 Transmission and Dana 300 into a 1986 CJ-7 that originally had a 4.2L, AW4 and Dana 300. Just to warn you some of this is pretty elementary and obvious.

What you need if you’re doing what I’m doing (I wrote how much I got it for and where I got it from):

4.0L HO Engine….$180.00 (included all accessories and flywheel) - Jeeps Unlimited (ebay is awesome)
Manual PCM….$125.00 - Jeeps Unlimited
Wiring Harness….$100.00 - Jeeps Unlimited
AX-15 Transmission….Free - Friend
AX-15 Bellhousing w/ CPS….$65.00 - Jeeps Unlimited
AX-15 Master Cylinder w/ slave line….$20.00 - Jeeps Unlimited
YJ Manual Pedals….$25.00 - Jeeps Unlimited
Dana 300….Mine
Dana 300/AX-15 Adapter….$130.00 - Novak Conversions (including shipping)
New Motor Mounts….$12.00 - Advance Auto Parts
Serpentine Belt….$26.00 - Advance Auto Parts
Speed Sensor….Free - Another Jeep
Water Pump….$35.00 - Advance Auto Parts
Clutch Kit….$200.00 - Advance Auto Parts
Pulley & Fan….Free - Another Jeep
Inline Fuel Pump….Mine

There is more stuff, but those are the major components. I was able to trade a T-176 tranny that I had from an old jeep of mine for $335 worth of parts. So that took care of the PCM, Harness, Bell, Master cylinder, and pedals. The AX-15 I got was a trade with a friend that swapped his out for an NV4500…I gave him some old full steel doors that I had. So in total I spent approx. $575 on the entire swap. The parts that are free were either mine or from a Jeep that I just pulled an engine out of for my step brother. I almost didn’t buy the clutch kit either considering I had one for the application but I figured I’d put a new one in since I had the drivetrain out of the Jeep.

Sensors
You need all of them. Hopefully you got most of them with the engine. Some that you probably don’t have but need:

VSS (vehicle speed sensor) – get it from a ’91 wrangler, it has the connection for the wiring harness and your speedo
CPS (crank position sensor) – if you are using your CJ tranny then you need to make some adjustments, I recommend this Hesco kit, otherwise you need a new bell housing from advance adapters or you need to cut a hole in yours.
MAP (manifold absolute pressure) – just buy a new one

I think all of the other sensors you need are on the engine, unless the guy you bought it from is really cheap and took ‘em all off.


I’ve pulled engines and installed engines into jeeps before, but nothing that entailed modifications like these, they were usually just direct bolt ups.

Removal
To start, you need to remove the entire drivetrain. Drain the radiator and take the grill off. From there you need to just start disconnecting all of the wiring harness and vacuum lines. Try to be careful because you may need some of these parts for the new engine. Remove the driveshafts, and disconnect the exhaust (I used a reciprocating saw and cut it off right after the manifold). Disconnect the power steering hoses. Unbolt the motor mounts. Prop the trans-case up with a jack and take off the skid plate. Double check that you have all the fuel lines, linkages, wires, hoses, etc. disconnected from the engine. Also remove the starter to give yourself more room.





Remove the drivetrain using an engine hoist.



Now that all of that junk is out of your way, take this time to clean out the engine bay. I used a pressure washer and some degreaser. The old engine used to leak oil like that’s what it was meant for, so this step was necessary. I spray painted the inside of the fenders and the firewall. You should also take this time to install the new PCM on the firewall or wherever you choose. Before you install the new engine, take the time to do the necessary modifications.

Fan
The engine was from a Cherokee so the fan was offset to the right. There are two ways to fix this. 1) Buy an electric fan. 2) Buy a Wrangler water pump and find a pulley and reverse rotation fan with a clutch from any wrangler with a serpentine belt. I chose the latter. Just replace the water pump and assemble. You will probably need a puller to remove the pulley on the old water pump.

Manual Pedals
I also decided to install the new manual pedals and master cylinder while I had the engine out. It’s fairly straight forward, and the pedals should bolt right up. I had to swap the sensor for the brake lights, it should slide right in. To install the new master cylinder, a hole for the piston, and mounting holes need to be drilled into the firewall. I don’t remember the exact size drill and hole saw I used, but when I find out I will post it.




Fuel Pump
I also installed the fuel pump while the engine was out. The fuel pump is another disputed subject for the 4.0 swap. Some people recommend taking the entire tank, sending unit and pump from the donor vehicle. I didn’t have that option, plus I already had an inline fuel pump from another CJ I just parted-out that had TBI. If you choose an inline fuel pump, the pump you choose needs to be able to supply about 40 psi to the system for an OBD I engine (everything before 1996). For anything after that (OBD II) it needs to supply about 45 psi. Don’t forget to install a fuel filter into the line as well.

Motor Mounts
One of the more difficult items on the list for me was removing the old motor mounts on the 4.0L engine. You need to replace these motor mount brackets for those that were on the 4.2L. Of course Daimler Chrysler decided to use Torx head bolts for these mounts. If I hate anything in the world, it is torx. The bolts were obviously frozen inside the block and it is impossible to apply enough force to the bolt with a torx head without stripping the bolt or breaking the torx bit (which I did 3 times). Unfortunately I don’t have an acetylene torch to heat them up, but a torch and MAPP gas from Home Depot did well and I was able to remove the right side mount. I did not have that luck with the left side mount under the manifold. After a lot of cursing and thinking, it was decided to use the grinder with a cutoff wheel, hack off the entire bracket and chop off the heads of the bolts, and use the remaining studs sticking out of the block as just that for the other mounts. 20 minutes later the bracket was off, and just to add on top of that the studs had loosened up and I could remove them with my hand. Now you can install the brackets. One thing to note is that one of the holes on the driver side is different from the other two. It is an M12 – 1.25x25mm bolt available at many hardware stores.

Drivetrain Adjustments
I am also replacing the clutch at this stage. Since I am using an AX-15 tranny and not a CJ tranny, there are no special adapters or anything for the bell housing. It bolts right up. If you are planning to keep your original tranny, then adapters can be found here: http://novak-adapt.com/ or here: http://advanceadapters.com/ .What I did need was an adapter for my trans-case. I am using the Dana 300 from a 1980 CJ-7 (it has a shorter output than other years). I chose the kit from Novak, but one can be found from Advance Adapters as well. The Dana 300 is very strong, reliable, and is a passenger side drop, so I see no reason for using something else.

This is basically the step that I'm at right now. I can post more pictures later, and when I go home this weekend. Unfortunately I can only work on this on weekends, because I work and live in RI until thanksgiving, and it would be too much $$$ to drive the 2 hours home to CT everyday. So it is strictly a weekend project, and hopefully its completely done and ready to drive by the time I go back to RIT this winter. So more info will be added after next weekend.

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Unread 09-11-2007, 09:25 AM   #2
gjohnson
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update for supraman1990

got some more work done on the jeep this past weekend

this is the whole drivetrain, with the 4.0, AX-15 (new clutch kit) and dana 300, with novak adapter and twin stick shifter




twin stick for the D300 i got from 4x4 machine shop off ebay


headers had a crack and needed to be welded earlier that day




the 4.0 installed and started installing the harness




first time this jeep has ever had this thing sticking up through the middle


installed maunal pedals





I got a lot done this weekend cause I wasn't drinking all day saturday, so I didn't even have a hangover sunday, which equals less mistakes and more motivation. thats about it for this past weekend, hopefully the thing will start up this upcoming weekend but i still have a lot of little parts that still need buying though
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Unread 09-11-2007, 11:10 AM   #3
supraman1990
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Thanks for the update man. I'm interested to see how you do your harness. That is what scares me with mine. I would want to thin my CJ harness of all that wasn't needed and thin the engine harness as well.
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Unread 09-11-2007, 11:33 AM   #4
gjohnson
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yeah, im still debating what to do with the harness. I have a complete under dash harness from a YJ too, so I was thinking about just converting the whole thing. It would basically just involve connecting the entire engine harness, connecting it to the bulk head and then replacing the harness under the dash, which im pretty sure is almost identical to the cj (except for the gauges). It would basically just make the engine wiring incredibly simple and the dash wiring hard. Instead of having to splice wires into the new harness, and weed out the stuff I don't need. I also have a YJ I can take gauges from so I think I might go with that strategy. Still up in the air though.
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Unread 09-17-2007, 03:07 PM   #5
supraman1990
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I want to go original looking, I want the only thing that indicates me having a 4.0 aside from opening the hood is my ability to rev to 6 grand.
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Unread 09-17-2007, 04:35 PM   #6
gjohnson
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yeah i actually got most of the wiring and little stuff done this weekend. almost got to actually turn it over but i think i have a bad ground somewhere, and I think it is the neutral sense wire for the starter ground. the fuel pump is also giving me headaches, its kind of old and the terminals have just about had it. I think im just going to install a tank from a different jeep that already has the pump in it. I also decided not to use the under dash harness from the YJ. I think I have a pretty good idea how to get by without it and hopefully im right. if most of the write-ups that i have read are accurate then wiring the harness into the cj is pretty simple.

What ive hooked up so far:

1) yellow wire for starter relay in YJ harness to light blue wire in CJ harness from ignition switch

2) red wire from yj harness to cj dash feed

3) dark blue wire from yj harness to red/white wire in cj harness for run/start

and I still have to figure out that starter ground which is a brown/yellow wire coming out of the relay, and hook up the fuel pump
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Unread 10-10-2007, 07:16 PM   #7
supraman1990
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Any update?
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Unread 10-10-2007, 07:21 PM   #8
supraman1990
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Any update?
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Unread 11-19-2007, 06:39 AM   #9
supraman1990
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I know I'm bringing this back from the dead. However, updates? Did you ever get it running?
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Unread 11-19-2007, 07:47 AM   #10
gjohnson
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you know if you asked me that question 3 days earlier I would have had to say no, there was no update. but interestingly enough I actually got it started this past weekend. I've been spending the past few weekends troubleshooting the wiring, because I had no spark. Eventually I figured it out and she started right up, of course it had no exhaust, and I dont even have the skid plate bolted up, but it started which was nice. so any questions?
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Unread 11-19-2007, 09:38 AM   #11
supraman1990
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I need wiring help. I forget the basic wiring stuff. Like which wires from the YJ to splice in to CJ. And what you need to run to the fuel pump to make it work. CJ Offroad appears to be down, and it's at my most crucial point, the wiring.
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Unread 11-19-2007, 09:57 AM   #12
gjohnson
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ok wiring is relatively simple now that i've figured everything out. First what year and model did you get the computer and harness from? And you are putting it into an '80??
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Unread 11-19-2007, 02:35 PM   #13
supraman1990
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Harness from a 92 XJ, computer from a 94 XJ, and engine from a 94 YJ. The harness is a brand new pre-terminated Painless harness, but it is going in to my 80 body.
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Unread 11-19-2007, 02:39 PM   #14
pkt1213
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Just kinda wondering why you didn't do a stroker?

If I get my 4runner sold I'll be doing a stroked 4.0 conversion soon.
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Unread 11-19-2007, 03:39 PM   #15
gjohnson
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a friend of mine built a stroker. it ran great for three months then she started struggling and right now it just sits in the parking lot up at school. I would have liked to, but I just dont have the time, money or the resources for it right now.

as far as for the electrical:

you only need a few connections to fire this baby up, but for the gauges and such a few alterations need to be made which I haven't gotten into yet. So to start off you need to supply a battery feed to the dash and iginition switch and what not. Im not sure what your painless wiring harness is like but if it says painless then it should have all this stuff labeled.

1.) So your taking the solid red 10-12 gauge wire from your xj harness where it would plug into the fuse block on the fire wall and splicing it into the feed for your dash/ignition switch.

2.) Then your taking the solid yellow 14-16 gauge wire from the xj harness and splicing that into the wire coming from your ignition switch for crank. (this is the feed to the starter relay)

3.) Then take the solid dark blue 14-16 gauge wire from your xj harness and splice that into the wire for crank and run. (this is the wire that f*cked me up because in my harness the wire is yellow/white). what you need to do is check your xj harness PDC and check what color wire is feeding your ASD relay. if it is yellow/white then connect that one...if it is dark blue then connect that one.

4.) Not sure what fuel pump you are going to use, but I did the E2000, got it for $80 and the wiring is simple. just ground one side. the fuel pump connection has three wires. just check which color wire is coming out of your fuel pump relay and connect that to the positive side. (mine was dark green/black).

5.) you may have to ground your starter relay. its called the neutral sense wire. they use it for automatics, but my harness came out of a manual and I had to do it. it should be a brown/yellow 14-16 gauge wire, and it will be coming out of the ground side of the starter relay.

that should be about it. ask away with the questions
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