1987 Ranger 2.3 to 1991 4.0 Engine Swap.

[Alexander]

I currently have a 1987 Ford Ranger with a 2.3 straight 4, EFI and 5 speed Manual, RWD. The engine started leaking oil bad and needed to be rebuilt, but I have a 1991 Ford Ranger with a 4.0 V6 EFI 5 speed Manual RWD, with a snapped Frame. I still need to test the 4.0 to be sure it's performing well. But I was curious if a swap was more worthwhile than a engine rebuild? Since I'd get more horsepower and torque out of it, at the cost of gas mileage of course. Also I was curious bout how to do the swap?

I was considering swapping the 2.3 for the 4.0. I'm not exactly sure how to do this. I think I'll need to swap the engine mounts, the Exhaust Piping, the ECM module and the fuel Rail System. And I was curious if the Transmission on my 2.3 will bolt up to a 4.0 or if I need to use the 4.0 transmission. If I do use the 4.0 Transmission do I need to swap the Rear Differential too? Can I just swap the ECM and plug and play or do I need to rewire and/or Flash some of the components? And what other issues would I run into doing this swap?

 

[RonD]

Welcome to TRS

Yes, you need to swap engine with its transmission anytime you change the size of the engine

Yes, you need the computer with its engine wiring harness when you change sizes as well

Yes, you will need to use the 4.0l engine mounts on the 1987 frame, and the transmission mount as well

Shouldn't be to much interfacing of wires since both vehicles are EFI and OBD1

You do need to separate engine wiring harnesses from body wiring on both vehicles

Good page to Bookmark here: https://www.therangerstation.com/tech/
Go to the Engine section
Scroll down to V6 Swaps, have a look at some of the articles

Most swap in a 4.0l to a 2.9l Ranger which has less steps since they used the same block so transmissions match up and have same(almost) exhaust

 

[rusty ol ranger]

Your 87 rear axle will be fine for the 4.0 just to add to what ron said

 

[gaz]

@Alexander ,
What kind of mileage were you pulling with your 2.3l, the OHV 4.0l was rated as high as 23.8 mpg highway for the 4 door 4x4 Explorers of that era while a 2 wheel drive Ranger was rated 16 city/24 highway.

I do not know when 8.8's were first used on Rangers but if your 91 has the 8.8," rear axle, that is something to consider depending on the gear ratio: on that note alone, the 91 will offer 10" rear drums and may have a better gear ratio for your intended goal tire size, may even offer a limited slip carrier

The driveline flanges for 4.0l are different, so take a look at both the driveline and axle flanges before you scrap the 91.

Even if a rebuild is not necessary, these three processes are worth considering for a known working, used Ford 4.0l OHV:
• have a performance valve job done, including new valve guides/seals. After years of use with the non-adjustable valve train, the valve seats can be expected to horrible, even if only 140k-190k miles.
• remove the rocker arms, disassemble, clean and inspect the components. Pay particular attention to inside the rocker arm itself (undoubtedly caked with sludge), unless someone else has previously performed this (presently), the assembly will very much improved by both a good cleaning. If serviceable, there is a remarkable benefit from deburring the parts, opening the oiling orifices one drill bit size, followed by a chamfer and buff. The results of this process are improved too end oiling/lubrication delivery.
• insure that your valve train benefits from proper lifter preload; without it, the valve train will be less efficient and experience increased wear.

A serviceable, properly adjusted valve train will ensure the highest possible efficiency ..)

 

[Alexander]

A little insight, I had snapped a Yoke flange when I got the 87 ranger, so I took the flange off the 91 ranger. The 91 ranger driveshaft was larger in diameter so I had adapt the input shaft to fit the Yoke Flange. You can see better what I mean in the photos.

I think the 91 ranger driveshaft is designed for more torque in comparison to the 87 driveshaft. I know spec wise the 4.0 V6 puts out 225 lbs-ft while the 2.3 I4 puts out 130 lbs-ft.

I don't know if the size difference in the rear diff in the 87 (7.5) and 91 (8.8) is to account for the torque difference or Axle Strength?

It seems to be based on axle strength, if so I should be able to use the 87 Ranger rear diff.
But I still have to mess with the driveshaft either adapt my current one to fit or pull one off a 91 ranger. Can I just cut the 87 driveshaft Slip Yoke Ujoint and weld the 91 Slip Yoke Ujoint, similar to how I did the Yoke flange so my current driveshaft will fit the 91 transmission and the 87 rear diff? Or due to the torque difference should I use a driveshaft off a 91 ranger?

Also does anyone have any thoughts how my input shaft would hold with the added torque. It's held up to 130 ft-lbs the last three months. Should I look into getting an adapted in Input shaft?

 

[scotts90ranger]

Dumb question but why didn't you just take the flange from the '91? The flange on the axles changed in '90 to use 13-10 U joints instead of the smaller one... everything else stayed the same. No matter what axle they had the same axle shafts but the flange was different between 7.5 and 8.8 from the pinion spline difference which I imagine was your reasoning...

The rest is fine, I wouldn't stress whichever input shaft you're worrying about, I'm putting twice the horsepower my M5OD was designed for to it and it's fine...

 

[Alexander]

I've reached a point where I've got the 4.0 V6 pulled from the 91. I was sketching up a wiring diagram that converts the 2.3 to the 4.0 based off haynes drawings of the two. I was curious if any of you would give it a look and tell me if there's anything unnecessary or if there's something wrong with it. My 87 ranger with the 2.3 has an ammeter while the 91 ranger with the 4.0 has a voltmeter I believe I figured the wiring out right. It appears the meters are just galvonmeter wired as either voltmeter or ammeter and so I should be fine wiring it the same as it was for the 87. I'll post the drawing in this post. The hand drawn one is my draft for the wiring conversion. The printed picture is the 4.0 v6 wiring from 91 and the web page is the 2.3 l4 from 87.
Also I'm trying to figure out what I'm gonna do with the engine while it's out. I'm gonna clean it and probably paint it but mechanical speaking I'm replacing the Timing chain and components, cleaning the fuel system, cycle oil through the engine when I get it running, replacing all gaskets. New Spark Plugs, and filters. I don't think I'll have to pull pistons and stuff as it had ran with ether and ran a few months before when it was on the road. But are there any thing to consider while I still have the engine out. I appreciate the help, God bless y'all.

 

[Alexander]

Dumb question but why didn't you just take the flange from the '91? The flange on the axles changed in '90 to use 13-10 U joints instead of the smaller one... everything else stayed the same. No matter what axle they had the same axle shafts but the flange was different between 7.5 and 8.8 from the pinion spline difference which I imagine was your reasoning...

The rest is fine, I wouldn't stress whichever input shaft you're worrying about, I'm putting twice the horsepower my M5OD was designed for to it and it's fine...

I would've done that but I had sent my driveshaft to be repaired with the flange off the 91 and they welded it on and threw a ujoint on for it. When I got it back I noticed that it didn't fit the input shaft for the 87 rear diff. So I tried using the other input shaft from the 91 but it didn't match the tooth pattern as the 87 if I recall correctly. So we quickly modified the 87 input shafy so we could get her driving. Sorry bout the late reply been busy with work.

 

[RonD]

Amp Meter and Volt meter are 2 different things

Volt meter is just hooked up to Key on power in the cluster

Amp Meter needs a Shunt on the alternators B+ wire from alternator to Vehicle
A Shunt is a smaller gauge wire than the B+ wire so has higher resistance
Most of the AMPs travel from alternator to vehicle on the larger wire
A few AMPs will travel thru the Shunt wire, which is hooked to Amp Meter
If hooked up correctly the Amp meter will show a +(charge) with alternator working, with key off alternator off no charge or discharge, if alternator should fail then Amps would flow from battery to alternator on B+ so Amp gauge shows - (Discharge)
Basically it shows the direction the AMPs are flowing on the B+ wire, to the vehicle(charge) or to the alternator(discharge)

The Shunt wire size is important as you do NOT want 50amps flowing thru the firewall to the cluster, it would blow the Amp gauge in any case and not a good idea
Look at the 2.3l alternator wiring harness you will see the Shunt wires on the old B+ wires
Looks like the red and yellow wires on the last diagram are the Shunt