The 4.0-liter engine is an ideal engine swap for 2.9 and smaller Ranger engines since the 4.0-liter is available in the Rangers and Explorers. This will give you an idea of what is involved and is a condensed version of on an article printed in the October 1997 issue of Four Wheeler Magazine.


Park your Ranger next to a 4.0L Ranger if possible and compare the engine compartments. Take detailed notes on the location of the ECU, wiring harnesses, air intake, electrical system, fuel line connections, and plumbing for cooling and A/C. Vehicles earlier than the 1994 model year appear to be the best donors for this job since many of the swapped components replace similar or identical items in the recipient vehicle. 1995 and newer models have layout changes that would require extensive adapting. Take photos of the 4.0L engine with all the components still intact for later reference. Obtaining a copy of Chiltons Ranger/Explorer/Mountaineer 1991-97 Repair Manual #26688 will give you the layout of the engines wiring, component locations, and vacuum line diagrams. When you begin disassembly of the 4.0 remember to label everything you disconnect in a manner so that you can easily reconnect them later. An example would be to use masking tape and start with the letter ‘A’ and label each wire connector (Male and Female sides) as ‘A’ to re-connect later. Go through the alphabet and then start double letters (AA,BB..etc) and continue.


Transmission compatibility is a consideration in this swap. Several transmissions were offered in the Ranger over the years. The one common factor is the engine to bellhousing bolt pattern which is identical for all years. The early model manual transmissions have a shorter input shaft with the pilot bearing in the flywheel, while the later years are longer with the bearing in the crankshaft. Of equal concern is the light duty design of the early model, which makes it more vulnerable to breakage. Newer model transmissions use a slave cylinder inside the bellhousing, so you’ll need those components and the interconnecting tubing if you elect to swap one in.

Automatics are equally varied. Units that normally mate to the 4.0 have electronic controls by the engine computer for overdrive and torque converter lock up. It is possible to swap in an early transmission, but you will have to fabricate a terminator that emulates the auto-trans functions that are missing, or use a computer and wiring harness for a manual transmission set-up. Early trucks use floor shifters, while the explorers and later rangers have column shifters.

Fuel System

The fuel system also requires attention. Later models with EFI will be the easiest. All that’s necessary is the adaption of the quick-connects for the fuel send and return lines in the engine bay. Both dual and single fuel pump configurations provide adequate pressure and flow for the new engine. If you’re replacing a carb setup in an ’85 or earlier model, you’re facing a complete changeover of the fuel system. You’ll need everything from the tank to the engine. The fuel injected engines use an in-tank fuel pump which operates with much greater pressure than a carbureted engine.

Air Conditioning

Air conditioning systems have some configuration changes between 1992 and 1993 models. Pre-1993 models used the same receiver/dryer and evaporator, so obtain an A/C hose setup from a 1992 or earlier engine. The hose assemblies will have the condenser connection on the left side of the vehicle, which mandates a condenser change. The newer style condenser bolts directly into place, making this an easy change. The compressor should come with the new engine and have no interchange issues.


At least four different electrical variations were offered over the years. Use either the Chilton book mentioned earlier or the proper Hayes manual for your Ranger. You’ll need to review the sections appropriate for your vehicle and the donor to determine the correct splices. Fortunately, unique color codes are used, which make the work more foolproof.

Electrical mods can be facilitated by acquiring a few key components. First, use the power distribution system found on the newer vehicles. It simplifies the integration of the charging, power distribution and engine control systems. An added bonus is the 10 to 12 heavy duty auxiliary circuits that can be adapted for accessories such as aftermarket lights, stereo, and other electronics. Verify also that the computer and wiring harness match the transmission that your using. While the different versions may appear the same, there are subtle differences in the wiring harness and programming differences in the computer that will show up later. Obtaining connectors with 12-inch pigtails that mate with the computer wiring harness will smooth the splicing work and maintain the modular nature of the system.

There are also wiring changes to consider. The later model alternators use external regulators that require a sense wire with a current limiting resistor from the main power system. The 4.0 V-6 has a tachometer connection in it’s wiring harness. However, due to the distributorless design, the signal it carries may not work with an existing tachometer. Finally, determine the correct splices to make for the fuel pump, ignition power, starter, power lead to the underdash fuse panel, A/C cutout relay and ammeter or charge light.

Bolting It In

The only custom work here will be drilling mounting holes or using a hack saw. Use the 4.0L factory motor mounts. Verify that the engine is complete with all belt driven accessories, intake and exhaust manifolds, crossover pipe, catalytic converter, starter, throttle cable, and air induction system.

Take the time to lay out all the parts in their general locations and in relationship to one another. Ensure that everything you have mates correctly before it’s installed. This is the time to service and replace any bad or worn parts.

Remove the engine following the guidelines in your Hayes or Chilton’s manual. Once the engine compartment is empty, this is a good time to drill any new mounting holes and perform any necessary fuel system upgrades.

Install the new engine and transmission. Next, install the new computer and wiring harness. These locate in the same place and follow the same routes as the originals. Mount the fuel pump inertia switch adjacent to the computer, and the power distribution panel near the starter relay. Connect the harness to the engine, power distribution panel, vehicle speed sensor and alternator. Then route the remaining connectors to the general areas of the A/C cutout relay connector, fuel pump connector, ignition and power connectors, and carbon canister valve. Mount the electronic distributorless ignition module on the radiator support between the radiator and the right side headlight; then connect it to the computer wiring. Use the original wiring harness connections for the temperature oil pressure sensors.

Install all the engine components and the exhaust as outlined in the Hayes or Chilton’s manual. Install the throttle cable.

Electrical work comes next. Install the color coded wiring using your manual and following the labels you made earlier. Early model Rangers will require the addition of a check engine light. Install any fuses and reinstall and reconnect the battery. Replace all the fluids and check for leaks. Start the engine. If all has gone well the engine will start on the first try. Check your work and check for leaks. Perform a diagnostic check. Once the diagnostic checks are done and the faults corrected it’s time to have the A/C serviced and recharged. In some states it may be necessary to get an emissions certification before you can register your Ranger.

Comments From Those Who Have Done It……

By jason_paul

here’s an answer to the eternal 4.0 swap question. Thought it might be useful since there seems to be a few questions on this recently.

ok, yes it is possible to do it in a weekend if you know exactly what your doing. If you’ve had the motor out of your truck or pulled one out of another similar truck its really easy.

I did my swap and ha the 4.0 parts truck in my driveway so here what I did.

I started with the parts truck. Pulled the radiator/air intake/battery out. labeled all connectors a and a and so forth. Disconnected all the hoses/throttle cable/drive shafts. removed the y-pipe and cats. Removed the transfer case skid plate then the transmission mount. lowered the trans / transfer case down and THEN took out the transfer case.

I decided to use the trans that the 4.0 was attached to, but if you decide to keep your trans, it is still easier to get to the top bellhousing bolts by tipping the trans down.

If your pulling the trans, you’ll have some more wires and hoses to label and remove. If its a manual trans, you’ll have to remove the shifter before lowering the trans. If its a manual transfer case, you’ll have to remove that shifter as well.

Next remove the engine mount nuts. Its easiest to get to them through the wheel wells. The 4.0 will have a stabilizer/damper on the drivers side. Re-use this on your truck.

then you should be able to pull the engine out. It is a tight fit if you leave the trans attached, but it will come out. It may bend the body seam on the firewall, but I didn’t care cause its not noticeable outside and can be bent back into place. Also, the fan is flexible and will bend when it gets to the front support. I ended up just lifting the whole front of the truck up and with all that weight, shook the engine hoist around and the engine “cleared” anything that got in the way. It sounds destructive, but wasn’t. Nothing broke!

Ok, Now you have the 4.0 out. It took me 10 days to do this by myself. Its just a matter of figuring out the little tricks to pulling everything apart.

Now on to the 2.9. Same as the 4.0 removal, but this only took me 5hrs!!!!, since I Knew exactly how to take everything apart.

Then you should be able to drop the 4.0 right in. You will reuse the 2.9 motor mounts. you’ll use the 4.0 exhaust, radiator, hoses, air intake/box, throttle cable, engine harness, computer, TFI (on the radiator support).

About the engine harness, my swap was from a 91 into a 90. I pulled all of the harness out of the engine compartment including the fuse box and lights harness. this allowed it to be a straight plug in swap without having to splice any wires. Everyone I talked to said I would have to splice wires. Well, my swap has 4,000 miles on it and everything works and NO wires where cut!

You’ll need the special tool for disconnecting the fuel lines.

other than that, email me with any other questions.

Doug’s Swap info-

My truck is an 83 Ranger 4×4, had a 2.8/auto in it. I used a 5 speed from a 4.0, heard that it is stronger then the earlier 5 speeds. you will need:

4.0 motor mounts, a/c condenser (has a line on either side), 4.0 throttle cable, 4.0 clutch hose, 4.0 cat converter and exhaust form the same wheelbase as yours, 4.0 trans crossmember and mount, fuel injected charcoal canister.

You have to redrill the right motor mount hole and locator pin. The hole for the bolt was 1 1/2″, the pin is in a different spot so use the mount as a template.

I had to open the shifter hole in the floor up some, and trim the heat shield also. The trans crossmember needs to be drilled also. The left side goes above the frame, right side 3/4″ below. I had to grind the barb off the master cylinder end of the 4.0 clutch hose to get it to fit into the older master cylinder.

Had to trim a little to get the a/c condenser in the radiator support. On a truck with factory air, if you get the 4.0 cond. and a/c lines, everything fits just like it should.

Stock radiator will hook up to the 4.0 hoses, whether it will keep it cool in the AZ heat remains to be seen.

Couple of different ways to handle the fuel system. You can use a fuel injected tank, internal pump, which cost me $165.00 with the sending unit, and then the external high pressure pump. Or you can use a carburetor tank, a Holley or whatever electric pump (5-7 psi) and then the external high pressure pump. If you go the second way, take a piece of the fuel filler hose out, replace it with a piece of metal tube with a fitting for the return line. If you go the first way, make sure you get a plug for the fuel injection tank for the sender unit because of the extra wires. I used metal lines all the way up to the engine compartment, with compression fittings hooking them up to the 4.0 fuel lines. You will need to get some of the metal lines from a 4.0 vehicle (down on the frame rail where they hook around and start to run down the frame). These are where the lines from the motor hook up.

The exhaust will use all the stock rubber hangers, at least mine did.

You will need the 4.0 starter.

The wiring depends on where the battery was in the donor vehicle. Mine was a 93 with the battery on the left side. The computer was tucked up under the dash from the engine compartment. Seeing as how I could not duplicate this, I had to extend almost all the computer wires. It sounds a lot harder then what it was. Keep in mind that Ford used the same color wires a couple of times in the harness, so just doing the one cut method is not advisable. I did them one at a time. If the donor had the battery on the right side, you will avoid this. On the harness that I had, even though the truck was a stick shift, the harness had all the wires for an auto. As far as hooking it up to the truck, if you don’t have cruise control, you have to hook up a wire to the brake light switch, to the start and run terminals of the ignition switch, and to both posts of the battery. The power dist. box also gets hooked up to the battery. If you use the oil pressure and coolant temp. senders for your vehicle, your gauges will work if hooked up. The starter is different on the 4.0, it has a cable directly to the battery and a signal wire to the switched side of the relay.

I would suggest going to the library and getting the schematics for your truck and the donor. This is how I figured out what I could eliminate, as my donor was loaded and had all kinds of extra stuff tied into the harness and power dist. box. Would also suggest that you try to find a donor vehicle that is still together, this way you get everything you need, airbox etc. The yard I got the 4.0 from even left the power steering hoses on the pump, which hooked up to my box with no fuss. Get everything that is associated with the motor, better safe then sorry.

This is all that I can think of right now, if you have any questions, feel free to ask. It is basically a very simple swap, and a whole lot cheaper than a v-8. Don’t get freaked out by the wiring, as it is simple. There is a red wire with a green stripe on the 4.0 harness that powers everything, this is the start/run wire that I mentioned. Other then this, it is like putting a set of driving lights on.

Hope this helped, If you can think of anything else that you might need to know, just let me know.

One final(?) thing. The Mazda 5 speed was difficult to find, I just stumbled across mind on another mailing list. The only other ones I found during a 3 month hunt were in the $1300.00 range. If anyone would like some information about a couple of shops that can build a tricked out a4ld, drop me a line. If all else fails, you can even use a c-4.

Good Luck,


Tom’s Swap

I’ll start by saying that, if possible, find a copy of the October 9 issue of Four Wheeler magazine. It has an article I wrote about swapping this engine into these trucks. It’s far more comprehensive than I can get in a simple message. Basically, though, you need the engine, computer, wiring harness, and all controls and accessories that connect to them. It’s a complete bolt in swap that requires no expensive adapters or fabrication. I did the whole thing with common tools. The transmission bolts up fine, the motor mounts can be reused, the computer mounts in the exact same location as the old one, the wiring harness follows the same path, etc. I used the same radiator, heater, A/C (with newer compressor on the engine) and had to connect about 12-15 wires into the existing wiring for things like ignition & start, fuel gauge, alternator output, etc. I used a Haynes manual to sort that out. One of the best things to do is park the two rigs side by side and make a comparison. You’ll be surprised at the similarities.

Eric’s Swap

I put a 4.0 in my 86 ranger from a 94 Aerostar I only had to change the computer. The radiator was the same for both 2.9 and 4.0 so that was fine. I have to put a clutch in now I’m not sure what to put in. But the clutch from 2.9 will work some what I have had it in there for a year and it was the old one then and Its starting to slip now.



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