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/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.
You need all of them. Hopefully you got most of them with the engine. Some that you probably don’t have but need:
(vehicle speed sensor) – get it from a ’91 wrangler, it has the connection for the wiring harness and your speedo
(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.
(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.
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.
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.
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.
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.
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.
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.