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6.2L GM "J" Diesel into a 1985 FJ-60 Land Cruiser

The first and most obvious question is why?

The 6.2L is not the best diesel. It's not even the best of the GM diesels. The 6.5L is a better version of the same engine. Toyota makes great diesels as does Cummins and Isuzu. These swaps have been done successfully. There's not a lot of information out there concerning the 6.2 swap and a lot of negative information about the gutlessness and reliability problems associated with this engine.

The answer is it's what I had.

I was given a 1985 FJ-60 with a blown 2F. Disassembly showed it had spun the number one bearing, destroying the crank and the rod. Number two crank journal was also scored. All six pistons showed signs of oil starvation and would need replacing. 2Fs are not cheap to rebuild. You can spend $800.00 on a re-ring kit without pistons. The cranks are not easy to find nor cheap when you do. It's just not that great of a motor to spend that much rebuilding it. It's heavy and slow.

I had recently swapped the H42 in my FJ-40 for a TH400. I had a Downey adapter plate and all the related parts left over on a shelf. It would cost very little extra money to swap to a V-8 with a GM bell housing.

I also had a 1988 Chevrolet G-30 1-ton van. The 6.2L diesel ran great and even had a newer transmission, but the brake lines were all rotted away. I had an 89 G-20 with a TBI 5.0L gas motor with 206,000 miles as well. Two motors, neither the best version of their respective genre. The diesel was in far better shape. I asked my wife, who would be the primary driver of the wagon which she preferred. She chose fuel mileage over ease of operation. I would also not need to do anything to the 6.2 and it would be a simpler install. Also, I have two Toyotas already with TBI small blocks, a 74 FJ-40 and a 93 T-100. Diesel it was.

Cheap and Fast

There is an old saying among mechanics; You can have it done cheap, fast or right. Two is rare and all three are impossible. This project needed to be done over winter break from school, (I am an Auto teacher) and for the least amount of money as possible, being that it was around Christmas. Corners would be cut to expedite the process. This is important. I would not normally post a hack job like this, but the lessons I learned could help someone decide if and how they were going to attempt this swap. You will see that I did not take the time to clean, sandblast, paint or otherwise pretty up the job.

Harvesting the Engine

The G-series vans used a unit body construction. The engine and the front suspension is held is a cradle bolted to the welded in frame rails. This makes pulling the cradle much easier than pulling the engine out of the front.

Remove any wire, hose or cable connecting the cradle to the frame, including the brake lines that snake over the frame rails on both sides.

You will need to remove the idler arm and steering box, or disconnect any portion of the steering linkage that will allow the cradle to drop.

The shocks can be unbolted at the top or bottom.

Remove the transmission cradle and support the rear of the trans. Remove the driveshaft and any thing else connected to the trans.

Remove the radiator. The trans coolant lines can stay with the trans.

Remove the 6 bolts, three on each side, that go up into the frame from the bottom. They are 19mm heads and you will need an extension. Two bolts on each side are between the motor mounts and the frame rails and, lastly, two bolts are above the upper control arm on each side. These are the easiest to get out, and should be the last thing you do. I used a vehicle hoist to lift the body off the cradle, but I would think a good engine hoist wrapped around the bumper could lift the van high enough to get the cradle out.

I did almost nothing to the engine. I couldn’t bear to put a motor in without changing the rear main seal as it was showing signs of leakage, especially with a Centerforce clutch. It’s just too expensive to have the oil wreck the disc. There were no other leaks. I did clean the engine reasonably well, but did not paint anything.

Transmission Options

The 6.2L is a heavy beast. About 60 lbs. heavier than a big block, I understand. It is probably mated to a TH400 trans. This an excellent trans for this motor for durability and will work very well with this swap. The downsides are that it sucks power the 6.2L does not have to spare, it is long and would require new drive shafts, and it is wide, possibly causing front drive shaft clearance problems. It does use a vacuum modulator for shifting. Diesels don't make vacuum, so it is run through a vacuum pump and switched using a vacuum switching mechanism attached to the throttle. Any trans with a Chevy small block pattern will work, but you must do some research to find which will work with the diesel. I believe the 6.2L was also available with a SM465 which will easily mate to a Toyota transfer case and will give you a creeper low gear. Again, you will have to do some research, as I believe the output shaft spline count on a SM465 late enough to be hooked to a 6.2 is wrong for the Cruiser. Also, the 6.2L uses a balanced flywheel or flex plate. You cannot use one from a small block, even if it fits.

Had I had the time and money to spare, I would have considered the TH400 adapted to the split case transfer case. There is an easy to use, excellent product from Advance Adapters. I could have used the extra length to better position the engine better and a cable operated shifter gives many more location options than a Toyota 4-speed or 5 speed.

Another good option would have been a Ranger Overdrive unit with the 4 speed. The 6.2L could use an OD gear and the added length would have placed the engine better. The Ranger fits between the Chevy bell housing and the Toyota trans and acts as an adapter as well. This is a very expensive option, but really would add a lot to the usability.

A third option to better place the engine would have been an adapter from Marks in Australia. It spaces the engine forward for the best placement. It is expensive, but much easier than what I used.

Other trans options are available. These are just three simple ones that would involve the least fabrication.

I chose a Downey adapter because it is what I had. I am not a fan of Downey products as every one I have worked with has needed modification to make fit. This one was no exception. The bell housing is one with bolt holes for a big block, small block or POB block. It has starter holes for left and right block mounted starters as well as trans mounted starter on both sides. This conversion must have a right hand starter location and a small block pattern. I fought with installation for an extra couple of hours because the starter nose cone on the diesel will not fit. It might be easier to install the bell housing on the block on the bench. I could not, (long story.) I also had to modify the slave cylinder. Another good reason to install on the bench. The 60 slave is on the right. The exhaust needs to come right through there. I installed the slave on the left, like a 40 series. For some reason, it will not bolt up to the Downey bolts. After trying a scab plate and having it not disengage the clutch, I shortened the shaft on the slave enough to use the Downey bolts. I used studs in place of the bolts so I could get the slave on without having to try to hold it in place and thread bolts at the same time.

The Downey adapter, like many manufactured for the csb /FJ-40 conversion is the stock depth. By this I mean the tip of the transmission input shaft rests in the end of the crankshaft in the pilot bearing. This causes the engine to be too far back in the engine bay. In order for the 2F to fit, the engine sat very far back in the engine compartment. The V-8 is much wider and will not fit in the indentation in the fire wall. Moving the trans forward causes problems with the shifter location and drive shaft lengths. The shifter lever is a serious problem on a 60 as there are ducts just in front of the shifter hole. An inch or two is the most you can go forward. The 6.2 is wide. The right side exhaust manifold exits the rear of the engine. There are not a lot of manifold options like a small block. Using a left side manifold on the right will not work as it would interfere with the motor mount. My solution was to clearance the firewall. At first I used a Big Freaking Hammer. Remember, fast and cheap. I think it might have worked, but the inelegance overwhelmed me and I cut out the firewall and rebuilt it with sheet metal. On the left side, there is more room. The head is slightly further forward and the manifold is not in the way. Still, I cut over to the steering column support, cutting out the throttle pedal mount. On the right side, the A/C evaporator is in the way inside the truck. I took it out as the 6.2 had no A/C, and the Cruiser A/C system was bad and missing many parts. Here you can learn from my mistakes. You must remove as much of the carpet and insulation as possible before even attempting to tack in sheet metal. The insulation catches fire if you look at it funny. I would pull the seats and all the carpet all the way to the seam. The right side must be cut just above where the head will fit in and back to the stock bell housing indentation. This is plenty far back to allow at least an inch and a half behind the heads for better air flow over the engine. It also must be cut to relieve the manifold and exhaust pipe along the trans tunnel. More cutting is better. You want enough room to easily move the engine around and be able to fab heat shields once everything is in place. The A/C evaporator box worked for a duct from the blower motor to the heater core, once a big chunk was cut out and a little sheet metal plate was put in. The bonus is that the heater core can now be removed with much less fuss. The brake lines and rear heater lines are also in the way on the right side, but not terribly so, just enough to make installing the engine a pain. I would remove the rear heater lines if I were to it again.

The throttle linkage was cut out so I used the throttle pedal from the van. It bolts up nice and flat to the new fire wall sheet metal. It would not work without spacing it back from the 60 firewall, but it would be very easy to make a little flat peice even if you didn't modify the fire wall. I purchased a throttle cable from a K3500 of the same year. It fit fine lengthwise. It has a square grommet so I cut a slot in the sheet metal and slid it in.

I used AA motor mounts because I had them. I didn’t like them and replaced them with the 6.2L stock mounts bolted to the AA mounts, mounted backwards and upside down so there was a mounting surface at the proper angle. I set the engine so it is level. There is a clearance problem to the lift pump. It is angled down right at the diff with about 3 inches clearance at rest with worn out springs. A lift kit would fix the problem. A spring over would certainly fix it. Neither is an option as my wife wants to use this truck for hauling dogs that are too old and fat to jump into my 80 series. I will probably use an electric pump and block off the mechanical one. Clearance is tight on the stock steering gear, but tolerable.

Great reasons for using a whole van for the conversion rather than buying a motor alone.

The van radiator fits very well in the 60. The 6.2L uses an oil cooler. If you use a 60 radiator or an aftermarket one, you will need an external oil cooler. The radiator sits perfectly on the frame rails with the little rubber bumpers. The upper radiator mounts fit into the stock 60 core support holes. This holds the radiator toward the engine off the support about an inch, but there is room to spare and it gives lots of room for any other coolers you want to put up there. The stock shroud fits well against the radiator. This also allows you to use stock van hoses. This is important as they are considerable larger in diameter than 60 series ones. I would think the 60 series radiator would be less than enough cooling capacity for the 6.2, but I have heard that others have not had problems using a stock 60 radiator. I did switch back at one point so I would be able to place the batteries in the stock locations, but it caused far more problems than it solved. The G-30 uses a pressurized overflow tank. This fits well in the old battery location.

The batteries could have been a major headache. I did not want them in the passenger compartment. With just a little more money, I could have put two spiral cells in the back with 4 gauge welding wire run to the front. That would have added another $250.00 to the project, but would have been a nice solution. It turns out that the trucks provided a very nice solution anyway. The stock 60 battery tray fits perfectly below the windshield wiper motor. In fact, the bolts line up with existing tapped holes with the brace angling up to one of the hood support bolts. It almost covers the A/C line holes, but in my case this was not a problem. I don't know if it would cause a problem with the A/C in place, as mine was mostly gone before I got it. I also had to relocate the washer bottle to the other side, but the carb fan was no longer needed so the bottle fits fine over there. I had to make a little bracket to support the top. The other battery fit very snugly in the left side of the radiator. Tight enough that it’s easier to remove the headlight washer bottle to get the positive terminal on. The G30 battery tray fits very well with a little trimming. The stock G30 cables are a perfect fit with the batteries in these locations. The G30 junction block was retained and mounted next to the wiper motor. The Toyota fusible links, (red and black wires off of the green round 3-into-one plug next to the battery) were wired into the GM fusible links off of the junction block and the white wire from the alternator must be hooked into a fusible link as well. I forgot this the first time and had a heck of a time figuring out why my blower motor didn't work.

The power steering pressure hose was a bit of a problem. Converting to -6AN fittings is a good option, but it cuts into both the time and money restraints to order the fittings. Instead I simply cut the steering box end off of a GM hose, installed the Toyota fitting and re-flared the end. Seems to work.

The van dipstick was too long. I cut it off, stuck the dipstick in the cut off part and cut the dipstick flush. Then I gave the stick a twist and a couple of lines and rounded off the end..

Really, that’s about it. There is very little wiring. The coil wire from the Cruiser, (black-yellow) is routed to the fuel shut off solenoid (Pink). The alternator light wire, (brown) is spliced to the Toyota (W/Y). The starter solenoid wire from the G30 harness is a fat purple one. The one from the Toyota is Black/White. The fuel line and the return fuel line are run right to the 6.2 lift pump and return lines. The oil pressure (Y-B) and coolant temp (G) wires will hook up to the Toyota harness. Whether they are the same values or not, I will have to see. I installed the glow plug light/ water in fuel light pod in the slot to the right of the steering column. The glow plug light seems to be very important to the glow plug system. I have been unable to get the glow plug controller to work right. To get it to run, I have replaced the controller with a Ford starter relay wired to a switch on the dash.

The air intake in the top pic was pretty neat, but the hood would not close and latch. The rubber hood sealing gaskets had to be trimmed for the radiator supports as well. The oil fill tube and air baffle do not hit.

It has been suggested to run the hydro-boost. I’m going to try to use the vacuum pump for less fabrication time. If the pump can’t keep up, I will try the huge vacuum storage canister from the van. If that still doesn’t do it, I will go to the hydro-boost. The way to do it seems like to get a Toyota bracket and mount that to the firewall and the hydro boost to the bracket. So far the vacuum pump seems to be working fine. We'll see how it does on Chicago highways, called moving parking lots in other places.

I have heard a concern that the 6.2L would be too heavy for the stock springs, especially in an old truck. The front actually appears to sit slightly higher in the front. I suspect the 6.2L does not weigh much more than a 2F and it does sit further back, with almost all of the weight behind the front axle.

It drives a lot like a 2F. Lots of torque. 4th gear starts are really not a problem. Low rev limit. There's no tach so it's tough to say how fast it's revving, but it sounds like it's time to shift pretty early. So far it's a blast to drive, other than a tight clutch. I don't know if the disc won't release all the way or the gear oil is too thick, but it is tough to get it to downshift.

So far:

1 88 G30 van free

1 85 FJ-60 free

1 Downey adapter bell housing leftover

1 Centerforce clutch and pressure plate leftover

AA motor mounts leftover

1 remanufactured 6.2l flywheel $62

1 new pilot bearing $8

2 new radiator hoses $24

2 new fan belts $20

2 gallons of antifreeze $14

7 quarts of 15W-40 CF oil $9

1 quart ATF for p/s system $2

1 oil filter $5

1 oil pan gasket $22

1 rear main seal $12

1 throttle cable $28

Total so far $206.00

Labor time this far including pulling the engine ~40 hours

6.2L stats 2F stats

386 CID V-8 OHV 257 CID, 4.2L I-6 OHV

1982-1993 1975-1988

Used in GVW trucks of less than 10,000 lbs. Used in 4X/55/60 Land Cruisers and fork lifts