Cummins r2.8 swap, 1975 FJ40 (1 Viewer)

[orangeyz]

Before:

After:

Enhance :

"If at first you don't succeed, destroy all evidence you tried"

Lurking and searching a lot since last summer, I saw a bunch of build threads peter out into nothing either because the builder loses interest, or finds out it's too much project, or gets it done and it's so disappointing they want to forget about it. And I know how that feels because all three of those happened to me on FJ40 Project #1 (2003-2010).
So I wanted to wait until I had something worth sharing before committing to a build thread, and three weeks ago I reached that point.
I drove this truck on the road for the first time in a year, and it was everything I hoped it would be.

1975 FJ40
Done by previous owner: Carb SBC with original 4 speed & TC, shackle reverse, power steering (Scout II, resembles FJ60 but isn't), extra gauges, mystery wires

New:
Cummins R2.8
NV4500 with Quickdraw bellhousing and 1969 TC with Advance Adapter Adapter
Dakota Digital Gauges
Rewired the whole thing
Brake lines needed some help
Needed a new heater setup as a butterfly effect consequence of the steering box
New fuel tank because of the giganto transmission
There's a Dakota cruise control box bolted in there that I haven't gotten around to wiring yet.

Last fall before the actual engine swap, driving it for the first time in 4 years, I got serious about investigating the "Brakes suck and handling sucks but that's just how FJ40s are" story.
Because if that was just how FJ40s are, I was going to bail on this project before it began and put the whole fleet on CraigsList.

Determined that the brake booster was ruined by leaking brake fluid, and rather than try to rebuild the original got one from a 1993 4Runner, which is almost a direct bolt in.
Now the brakes are awesome. Ok they still pulse and pull to one side, but that's a lot better than "Smash full strength and they barely work."

Also learned about caster and axle shims, and 4 degrees later it was like a whole new truck. Instead of sailing into the weeds every 40 feet I could take my hands off the wheel at 60 mph and it tracked perfectly.

So here it is:

If there's anything specific that you want to know about this project, ask away!
Otherwise, I guess I will get to it in the order that I get to it.

 

[Catching Neutral]

Your results are impressive. Reproducibility is where its at. You should do that to mine.

 

[orangeyz]

A bunch of this thread is going to be here's what I did and why I would not do that again, but overall I'm really happy with the end result.

NV4500 vs H55
Three reasons I would have not gone with the NV, and two of them are: it's big!
It's tall. If you don't want to cut or lift your tub, it's going to hang below the frame.
Before tub cutting:

Accepting that this is going to be ugly

It's not a show truck or a restoration or even a restomod though. It already had some hokey butchering going on, and now it's going to have some different hokey butchering.

End result of that choice

It's in there, and none of it hanging below.

It's long.

So the cross tube obviously can't stay there and had to come out, and I replaced it with a transmission crossmember which is a heavy piece of channel and bolted with clamshell mounts to both sides of each frame rail
Now that I'm doing this thread I realize how many things I don't have pictures of, I'll try to get more in the next few days.

The rear drive shaft ended up being about 4" long and kind of steep, so I needed to come up with some sort of double cardan shaft.
Searching here led me to first gen Tacomas, and the auto salvage yard about a mile away. The two piece rear drive shafts have a dc joint in the center. I have no idea why, because it's not a wild angle on those trucks, but they do.
95 to 04, newer than 05 is a standard u-joint.
Prerunner or 4x4 only, 5 lug 2wds have a regular u-joint. That one took a couple of days to straighten out with the parts guy, and I had to find a Tacoma on a used car lot and get a picture of the joint before he believed me.
And extra cab or longer, regular cab will probably have a one piece shaft with the standard joints.

So having bought the drive shaft, the easy part was over. Next up was pressing the studs out of the parking brake drum, drilling new holes offset 45 degrees, and opening the holes in the joint up a tiny bit.
The spline is the same between the Tacoma and FJ40, so that part was kind of easy, I just used the original half at the axle and then took it to the local driveshaft shop to get it shortened.
I'm still getting around to shimming the rear axle to get the second joint angle correct, because it's definitely not.

 

[orangeyz]

Mishimoto intercooler from Summit, 28x7.5x2.25"

I used Intercooler Pipe Fabrication for a bunch of stuff. Mostly the silicone intake parts, but also the radiator plumbing and they have a good selection of stainless tube I used for the exhaust.
Everything from the turbo to the intake is 2.5" and I used the 2.5" clamps on most of it, but the intercooler inlets are a very tight fit so I needed to use the next size up clamp on those.

Used a 3" to 2.5" reducer elbow from the Cummins intake tube to another aluminum tube, and then a 2.5" to 2" elbow from there to the turbo inlet.
The MAF sensor...doesn't quite fit on the supplied tube:

So I altered it by about 5"

I'll get a picture of it later on, but that tube also has a bracket welded to it to bolt to the fender

 

[orangeyz]

Out with the old

In with the new

Mocked up where the hood would close at

Don't want to leave any axle clearance on the table if I don't have to

Farmstrong universal engine mounts

Painted the mounts yellow because why not.
Making the towers was kind of an ordeal because we would get one side mocked up and move to the other side without realizing that the forklift holding the motor up was settling.
We got it done by making the frame piece and the top piece, and MIG zapping a small strip between them quickly while the motor was in the right spot, and then pulling them out and making and tig welding the whole box structure.

 

[orangeyz]

Making the fuel tank, part 1

Borrowed a friend's Harbor Freight level sheet metal brake, but it wasn't hurky enough for 0.100" Aluminum, 4 feet wide so we went to another friend with a bigger brake that did the trick.

Sump

 

[orangeyz]

Fuel tank part 2

It ended up at 18 gallons exactly.
We used the Classic Instruments tube sender and it matched up with the Dakota dash perfectly. Read empty when empty, read full when full, now reads a little under half after driving 240ish miles, so fuel economy is looking like it might turn out as advertised.

 

[orangeyz]

Cooling system
"The R2.8 CM2220 R101B engine is designed for use with a positive fully deaerating cooling system."

"A fully deaerating cooling system enables trapped air in the cooling system to be properly purged. The cooling system is comprised of a radiator, deaeration tank, fill line, and vent lines. The pressure cap on the deaeration tank should always be the highest point of the system. All vent lines must continuously run uphill until they connect into the dearation tank."

Ok, what? This is one of the chapters where I gotta be honest, the other builds everywhere on the internet weren't very helpful, and neither were the videos from Cummins. Googling "deaeration tank" showed a schematic of what Cummins does in theory, and no real world examples. It took a few days of deciphering, but I'm pretty sure I ended up with what they meant. If not, then I'm following the rule that the fastest way to get the right answer isn't to ask, it's to post up the wrong answer.

Deaeration Tank:
Water Header Tank, Vertical, 8" H x 4" Dia, without Cap - Pegasus Auto Racing Supplies

I cut and rewelded the mounting tabs and was able to use threaded holes that were already in the firewall. The top inlet needs to be the highest point in the pressurized part of the water system, and center of the engine bay near the back is what the hood allows.
If the oil filter, fuel filter and grid heater solenoid locations on the edge of the picture look familiar, it's because I read DDelong and Sheck's builds and thought "Well, not going to beat that!"

Somewhat plumbed in:

The 3/4" hose out of the bottom of the tank goes to the aluminum piece connecting the original radiator and the engine water inlet. Lots of bending reducers from silicone intakes and wire hose clamps from Amazon.

More plumbed in. The thermostat housing clocks 120 degrees from where it's installed at the factory, which is nice because then it points directly at the radiator.

The hose is tight and a huge pain to get on both the radiator and the thermostat housing, so I connected them once while they were out of the truck and in an easy position, and then the aluminum coupler between them is easy to go on and off with for removing the radiator.
Also pictured, the Dakota temperature sender, but the M12 adapter they included was the wrong pitch so I had to find another one.

Reposted photo of the end result, mainly showing the air outlets in front of the thermostat and near the top of the engine

Both the deaer tank and radiator cap outlets join under the plastic overflow reservoir

Replaced the heater valve with a new onc from City Racer, and there are approximately 70 hose clamps connecting that, the return, the engine and all of the adapters and elbows.

The original cable was rusted solid, but the choke cable was still good and not going to be used, so I shortened it and did some switcherooing.

 

[orangeyz]

Second fill up this weekend. 240 miles on the odometer, plus about 25 that happened before I figured out how to make the odometer work. Tank took 12 gallons.
265/12 = 22 mpg. So that's cool, especially considering I was warming it up for 10 minutes twice a day to drive 10 miles to work and back.

The Great Wiring Adventure, starting with my pet octopus:

I did not intend to rewire a bunch, as long as the original wires were good I was perfectly willing to live and let live and integrate the new engine into them.
But they weren't good.
In the pre-project test driving, ground problems and broken wires popped up for everything, there were a bunch of extra wires for an emissions computer that wasn't there and wouldn't be replaced, and all of the connectors were ready to explode into dust when touched.
So I resolved to rewire the whole thing.
It took about a month of designing it all, and then about three months of constructing the pet octopus relay box, replacing connectors on all the lights, laying out and taping up the wire harness from front to back.
I found different colored wire loom on Amazon that was pretty easy to figure out and order, so I took advantage of that to try to make things a little easier if I need to look at a problem in the future.
Wires in black loom are associated with the Cummins engine harness.
Yellow loom is lights, controls, and basically anything that is "The Land Cruiser"
Blue is Dakota Digital sensors and controls
Red is for hot battery cables
This worked pretty good until the end, when I would want a small chunk of a certain size and only had wrong colors available. So it's not perfect.

Since I started from scratch, almost none of the original Toyota colors mattered. I started with some sort of established standards and then made it up from there.
Trailers: Brown=tail marker, yellow=left, green=right, white=ground, reverse=purple, and trailer brakes=blue. Honestly, I don't know if that's a real standard or just what the first picture on google says.
Red=hot right now, black=hot when the ignition is on
That leaves orange for brake lights, and then it started to get ugly.

Finding wire with stripes is a little hard, and then there are usually 100 foot minimums. Using a 3 foot section of a color once is ok for Toyota, because 10,000 Land Cruisers are going to use 6 miles of wire, but I don't want 97 feet left over.
I used Corsa Technic for a bunch of connectors, and found that they have some striped wire available in some sizes, but it would have cost about $400 just to do the windshield wipers.

Then a coworker came up with the epiphany of using different colored heat shrink at each of a wire and I was off to the races.
With 11 easy wire colors and 10 easy stripe colors I didn't have to use anything twice.

This counts as something I would do again, but I would use those last three wire colors available and have less stripes, because those were a little tedious.

Rewiring everything was also an opportunity to do some things I wanted that might have been difficult otherwise, like have a headlight warning buzzer, not run all of the current for everything through a 50 year old ignition switch, and put some cooler reverse lights in

 

[orangeyz]

Shortened the interior Cummins wire harness in a few places, mostly the warning wires, and OBD reader and the tach. According to the Youtube videos you're not supposed to shorten the throttle pedal wires, and the Murphy gauge is on the far left of the dash so I didn't need to touch it.

This hole where wires went through originally happens to be the right size for the coupler, and the engine side harness can reach it even with the computer on the left fender

Warning light panel and Murphy Gauges

The logic that led me to make the warning light panel instead of just using the Dakota lights available was not quite perfect, and I probably wouldn't do it again, but the hole is already cut so there's no going back.
Cummins says: Need two warning lights, one yellow one red. Dakota only has one light, it's red.
Cummins warning light inputs are a ground connection: you send 12v constant to the light, the Cummins wire completes the circuit by setting to ground when needed. Dakota box wants 12v only when the light is on. Could have gotten around that with a relay, but would still have the not enough lights problem.
Same with the Wait To Start light, that would have been easy enough to connect the Dakota to the grid heater solenoid though.
I kind of wanted a big green 4wd light like Dad's Land Cruiser had when I was in Kindergarten.
Need a place to put the Dakota button anyway.
All of that led to: Make a panel
I was going for the 1984 FJ40 rare silver dash look, but then completely forgot to paint it silver before assembling it, and didn't feel like disassembling it.
That yellow check engine light that I put a lot of effort into having? Yeah, it's always on and I covered it in tape the first time I wanted to drive in the dark.

Oops.

What I would do next time, is put the Murphy Gauge on the right (like I've seen in almost every other build because it's a good idea) and a small hole for the button on the left.
Maybe two holes, one for the dimmer knob which is in the old choke cable hole now.

On to stuff that is working out, the LED reverse lights are really nice, and there are no extra switches to run them.

This relay is set up so that when the headlights are off, the original reverse lights are used. "Hey, just letting you know I'm backing up, don't want to blind you or anything"
When the headlights are on (taillights actually, so turning just the running lights on will do the trick) the reverse light power is routed to the LEDs.

 

[orangeyz]

5,000ish mile update: It's good.
I added the block heater in January and have been daily driving it since then, and it's very fun to drive.
No issues with the motor or conversion stuff.
All of my problems have been related to "It's a 45 year old project car"
Original radiator leaked, got the new one from Cool Cruisers.
Brake caliper leaked, found out that it does not have factory discs, the previous owner did the mini truck swap, got that figured out.
Power steering line leak, transfer case leak, clutch master leak...
New 10.5" BFG KO2s are way better than 20 or 25 year old Cooper 12.5" wide Mudders in every way, weird.
Almost every tank has been between 22 and 25 mpg.


Some info for others on the subject of the r2.8 and the stock FJ40 radiator

Short version:
Empty truck, good, regardless of terrain and weather
Truck loaded way too heavy, not good, especially in bad terrain and weather

Longer version:
The book says don't go above 225°F, and by wild coincidence that's also when the yellow light comes on.

In driving the truck from January to June, I never had it go above 185, usually hanging at 180.
We're about 4 or 5 weeks into a ridiculous heat wave, and at 105 outside temp I had the engine get up to 195, driving at 55-60, empty.

Last week I went for a dirt biking camping trip, and decided that for the hell of it I would take the Land Cruiser 600 miles through many mountain ranges to Central Idaho.
The limits of the cooling system were found immediately.
Halfway up the 8 mile 6% grade 5 minutes from home I hit 215°. Probably should have turned around and taken my Tacoma instead, since it was only 60 degrees in the morning and it was only going to get worse from there. But I decided to stick with the adventure and see what happened.

Holding 55-60 mph on level ground it would stay at 195-205°
It went pretty well until the Stinkwater and Drinkwater passes east of Burns around 1pm.
In 4th gear trying to maintain 45 or 50 mph up the pass, it shot up to 225 at the drop of a hat, about 30 seconds from hitting the base of the hill.
The good news is that when pulling over and idling it would get back down to 200 in less than a minute or two, and 180 after about 5 minutes.
There was no way to make any forward progress using 4th gear.
At 25 mph in 3rd gear, it would creep from 190 to 215, and I would make it all the way up the hill on the trip there. It was hotter on the trip back and I would have to stop and let it idle down, even crawling in 3rd.

On the way back, I couldn't keep it under 210 on level ground at 55mph, So I used a camp chair and rope to wedge the hood open about 6 inches, and that kept me under 200 usually.

Even pulling the trailer through the mountains and probably spending a total of an hour idling, I still got 22mpg on most fill-ups.

Got a cool picture out of the whole thing too

Work that I could possibly do to improve the towing without overheating:
1: The intercooler angle iron mounts I made block off about 40 square inches of radiator area, could cut those down easily.
2: More powerful electric or mechanical fan. That sounds like a winter project.
3: Different radiator and also intercooler set up. That sounds like a next winter project.
Problem that could come up is the opening through the bib might be the airflow limiter, and I'm not willing to chop it up to fix this one thing, so actually solving this completely might just be impossible.

None of these fix the issue that being in the Land Cruiser when it's 100° out is not a super fun time anyway, so:
4: Whenever the trip plan calls for "Drag a 3,000 lb trailer through the mountains during a heat wave," take the Tacoma!

 

[DaveNotHere]

Holy cow.......

Nice job. I was wanting to do this.

But now I don't think I got the talent.

I just hope I can somehow get my old 1976 back on the road again.

 

[1811Retired]

I had the same issue with my 60 after installing my R2.8…a duel fan was put in and helped a great deal!

 

[POPO AGIE]

5,000ish mile update: It's good.
I added the block heater in January and have been daily driving it since then, and it's very fun to drive.
No issues with the motor or conversion stuff.
All of my problems have been related to "It's a 45 year old project car"
Original radiator leaked, got the new one from Cool Cruisers.
Brake caliper leaked, found out that it does not have factory discs, the previous owner did the mini truck swap, got that figured out.
Power steering line leak, transfer case leak, clutch master leak...
New 10.5" BFG KO2s are way better than 20 or 25 year old Cooper 12.5" wide Mudders in every way, weird.
Almost every tank has been between 22 and 25 mpg.


Some info for others on the subject of the r2.8 and the stock FJ40 radiator

Short version:
Empty truck, good, regardless of terrain and weather
Truck loaded way too heavy, not good, especially in bad terrain and weather
View attachment 2742239

Longer version:
The book says don't go above 225°F, and by wild coincidence that's also when the yellow light comes on.

In driving the truck from January to June, I never had it go above 185, usually hanging at 180.
We're about 4 or 5 weeks into a ridiculous heat wave, and at 105 outside temp I had the engine get up to 195, driving at 55-60, empty.

Last week I went for a dirt biking camping trip, and decided that for the hell of it I would take the Land Cruiser 600 miles through many mountain ranges to Central Idaho.
The limits of the cooling system were found immediately.
Halfway up the 8 mile 6% grade 5 minutes from home I hit 215°. Probably should have turned around and taken my Tacoma instead, since it was only 60 degrees in the morning and it was only going to get worse from there. But I decided to stick with the adventure and see what happened.

Holding 55-60 mph on level ground it would stay at 195-205°
It went pretty well until the Stinkwater and Drinkwater passes east of Burns around 1pm.
In 4th gear trying to maintain 45 or 50 mph up the pass, it shot up to 225 at the drop of a hat, about 30 seconds from hitting the base of the hill.
The good news is that when pulling over and idling it would get back down to 200 in less than a minute or two, and 180 after about 5 minutes.
There was no way to make any forward progress using 4th gear.
At 25 mph in 3rd gear, it would creep from 190 to 215, and I would make it all the way up the hill on the trip there. It was hotter on the trip back and I would have to stop and let it idle down, even crawling in 3rd.

On the way back, I couldn't keep it under 210 on level ground at 55mph, So I used a camp chair and rope to wedge the hood open about 6 inches, and that kept me under 200 usually.

Even pulling the trailer through the mountains and probably spending a total of an hour idling, I still got 22mpg on most fill-ups.

Got a cool picture out of the whole thing too
View attachment 2742240

Work that I could possibly do to improve the towing without overheating:
1: The intercooler angle iron mounts I made block off about 40 square inches of radiator area, could cut those down easily.
2: More powerful electric or mechanical fan. That sounds like a winter project.
3: Different radiator and also intercooler set up. That sounds like a next winter project.
Problem that could come up is the opening through the bib might be the airflow limiter, and I'm not willing to chop it up to fix this one thing, so actually solving this completely might just be impossible.

None of these fix the issue that being in the Land Cruiser when it's 100° out is not a super fun time anyway, so:
4: Whenever the trip plan calls for "Drag a 3,000 lb trailer through the mountains during a heat wave," take the Tacoma!

I plan to use the Cummins R2.8 in my 78 FJ40 but I will stay with the H55F and the split transfer case I have planned. I am glad I kept reading after I saw you used the stock radiator and though I could also do that, but living in the SW of you in Wyoming I have passes to get over just to get to the south, west or northwest and I had cooling problems with the 2F and 155F on the highway.

 

[fjdiesel]

@orangeyz Do you have an update on what you did to the cooling system and how it worked?

 

[orangeyz]

@orangeyz Do you have an update on what you did to the cooling system and how it worked?

Last winter I had to take the front apart to fix a power steering leak, and while I was in there I cut the intercooler mounts down significantly. That helped by about 15 or 20 degrees on normal days, and 10 degrees on hot days like this summer has been.
Also on one day this summer I tried just taking the bib off during a drive, and it dropped the temperature by about 10 degrees. I wouldn't dream of cutting it up to help air flow, but just taking it off when needed is a pretty reasonable and easy thing.
I've got the motor mounted too high to change to a mechanical fan, and I don't think air pulling power is my problem since this all happens at 60 mph.

Good chance I take it camping over the mountains with a trailer next weekend, and I'll see how it does now.

If it still overheats and I don't want to just "Accept the project car's limitations" then I've got about a inch to work with and could put in the 4 core radiator that's been floating around in my garage for a couple of years.

 

[orangeyz]

Great news!
This post in a thread about overheating SBCs that just happened to get bumped recently made me realize that moving my radiator back meant that air was going around it instead of through.
So I made this thing

Which pulls air from the hood opening, and doesn't let anything get over the top of the radiator. Some air can still get around the sides, but not a lot.

It worked!
Put on a trailer real quick and went for a test drive towards the mountains

Gross Combined Weight, 5900 lbs
95° Temp, 5% grade.
I was able to maintain 45mph in 4th gear while teetering at 222 on the edge of overheating.
Pulled over to let some traffic by and let it idle down to about 195 and took off again. Stayed between 215 and 220 hanging at 45mph.
This is still with the stock radiator.
So it's still not a new Tundra that could pull a space shuttle up a hill with no worries, but way better than on the last attempt a couple of years ago, and probably equivalent to how normal driving life was in 1975.

@fjdiesel
@POPO AGIE