Here is the in-depth write-up that I hope can serve as a how-to for OM617-swapping 96-04 Tacomas/4Runners (and T100's).
I picked up this $600 1997 4Runner 5VZ/A340 4x4 (rear e-locker) with roughly 250k miles and it was SHOT! Completely rusted out even though the body doesn't show it. Destroyed interior. Radiator blew up and mixed trans fluid with coolant to make a milkshake in the trans. Now I haven't read a single report of anyone flushing their trans and successfully driving it after that. Even the ones done under warranty at the dealership with the power flush had trans failure shortly after. Keep an eye on your radiator if you've got an automatic! The PO claims he noticed it right away and had it towed home where I picked it up. I flush the trans, added a new radiator, and put another 30k on the 5VZ! I daily drove it to work, used it to tow the mower trailer around, and even drove it 3 hours into Iowa with the trailer to get a band saw. Did a fair amount of wheeling with it, too, enjoying the rear locker. Eventually, it started losing coolant, so the 5VZ got yanked and sold.
The plan for this has always been for R&D. The only money I have into this rig is the new radiator and mounting the free tires someone was throwing away. Sold the 5VZ to cover the purchase. Can't beat that! I'm currently swapping in an OM617. I'll be using the 4Reigner to test trails I'm cutting in our pasture, as well as haul the tree cutting equipment around. Since the frame is already falling apart, I don't expect to keep this around much longer. I had originally planned to do a TDI swap after the 617, but have since decided not to worry about making TDI adapters for the Toyota Automatics, as the torque converter pilot stub would require turning down, and that is probably too much effort for most people. Once the frame folds in half, I'll pull the 617 back out to go into something long-term, and I'll save the rear axle and trans.

I think theres a way around making flexplates.... wouldnt it be viable to provide the template and then have the customer take their existing flexplate to a machine shop ans have them drill the holes and balance it using your template?
Instead of a custom certified flex plate, why not get a performance Torque Converter from Precision of New Hampton that mates the engine flywheel and transmission?
I like your attention to detail. I have over the years owned 5 Toyotas and Three MB diesels. I also currently have a MB 560SEL with the European Engine.. My daily driver is a 1998 Tacoma Extracab SR5 with the 2.4 engine RWD. I have been planning a contingency of putting in a 1985 300SD OM617 motor for sometime. My Tacoma has the A43D transmission which is a 4 speed Automatic non-lockup converter. 1st 2 3 4 Rev
2.452 1.452 1.000 0.688 2.212
Its the same transmission used in the Toyota Motor homes.
The 300SD was designed such that peak engine torque was around 60 MPH
mating the OM617 to the A43D with the stock rear axle on my truck would put peak engine torque at 75 MPH.
I'm using this forum thread to gauge interest in a Toyota Automatic (A340) OM617 Adapter kit. Unfortunately, I haven't seen hardly any interest at all. Only 1 viewer post. Certainly not worth my time/effort to go out and design/manufacture and have SFI certified a billet flexplate for the adapter kit if no one even wants. This is one of the many pains of R&D and running your own business, though. Some ideas float and some sink - and this one appears to be a sinker. I was planning several major upgrades for Project 4Reigner to really make it the "showcase" swap for this adapter kit, but I will now invest that money into something else. I was also planning to finish updating this thread with all of the very specific instructions on the wiring modifications that were necessary to make the A340, 4x4, A/C, etc. work. I spent dozens of hours just deciphering the wiring. But again, it's not worth my time if no one is even going to do this swap.
The last update I'll make is this:
The diff gearing is paramount to this swap performing well. I tested smaller tires to simulate lower gearing, and the difference was night & day. I'm no longer going to invest in a new R&P setup as it would take me 20-30k miles to pay that off, and I'll likely be stripping this swap down so it can go into the next R&D rig. A custom torque converter would certainly benefit things. But I am surprised how well the factory 5VZ TC works with the 617.
I recently added a push-button Torque Converter switch from aironboard.com. Unfortunately they don't provide enough 3rd Gen switches - mainly just 4th gen and newer. So, I had to settle with a mislabled "Air Compressor" switch, but it works all the same. I simply spliced the switch inline of the TC signal wire. Switch on = factory TC signal. Switch off = TC unlocked (TC can't receive any signal).
If the TC engages, I can then toggle the switch on/off turning the lock-up on/off. However, if I shift from 2nd to 3rd with the switch OFF, then even when I press the switch ON, I can't get the TC to lock up. Oddly, I have to shift to OD before it'll engage. It's almost as if there's a 'condition check' that occurs when the TC should initially lock up in 3rd, and if it senses it isn't locked, then it bars it from locking as long as I remain in that same gear. I could, of course, overcome this by adding a 3-way switch so I could have lock-up ON, OFF, and Auto. But then you run the risk of forgetting it's on, and trying to hit the brakes and dying. I don't expect anyone to ever want a manual switch as I have it. I simply added it just as a band-aid for not having the proper diff gearing. It's worth 200-300 RPM in 3rd, which is the difference between falling on its face and being right at the start of the powerband when shifting from 2nd. Same story with OD. And, if I'm just cruising in OD and want my RPM higher, I am able to unlock the TC without the trans temp spiking. It does, however, go up quickly if I drive unlocked all the time with heavy acceleration.
The proper solution for the A340 with the OM617 is to get an aftermarket controller to allow modification of shift points and lock-up settings. Compushift still doesn't have inventory as of 1/11/23, and Haltech of Australia doesn't even have a functioning website now. Until tuning is available, I don't see this as a viable swap, unless you're building a rock crawler and want the torque multiplication and omittance of the clutch pedal.
My best tank during testing has been 29mpg. Still well short of the low 30's where I expect this swap to be when everything is set up correctly (gearing, shift points, TC stall, etc.). But it's a great sign of the potential this trans has to offer for diesel swaps (A340, AW4 married to OM617, OM60x, TDI, etc.).
Now that it's been down to 11°, I've had a chance to test the 5VZ-FE starter wiring, and it's failed miserably! If ambient is >50°, the OM617 will start just fine. Below 30°, there is no chance of this thing starting without having the block heater plugged in, because the starter just can't spin fast enough due to the small gauge wire.
The automatic-trans starter actually has a higher output than the manual, so it shouldn't have any problems with proper wiring. I'll eventually add a 2/0 battery-to-starter wire, to match the ground, and to match what I use in every other OM617 swap, and this puppy should start at 4° without being plugged in!
The Takeaway:
If you live in a southern state where the temp doesn't get below 40-50°, you should be just fine using the factory starter wire. If you're mid to northern US, or Canada, or Greenland, etc., you'll need to beef up that starter wire!
Haven't had a chance to test mpg - been fighting a new gremlin. The smooth GM pulley doesn't get enough grip to turn the vac pump without some slipping. Mind you, I still have brakes, but I also get a horrendous belt screech. I swapped on a new belt, thinking the failed ac comp stretched this one too much (which it did), but I had screech again almost immediately. There isn't a factory ribbed pulley that will work (that Dorman or I could find, anyway), so I'll be attempting to modify one that's close. Hoping to have that completed within 2 weeks. Then, I'll have to drop the radiator to swap it out 😪 Till then, I'm turning heads with either my belt whistle or the turbo whistle, adding the miles to the swap. Got my cup holder 3D printed, and I am now content with the interior creature comforts.
If you're reading this, the entire thread has been updated as of 11/12/22.
Did some wheeling this morning, testing out the low range, the 4x4, and in this picture, the E-locker!
Planning to check MPG with a couple different driving strategies. Will limit max speed to 2600 RPM in 3rd gear. Will also try driving any speed up to 70mph limited to 3rd gear (aka, no OD). Expecting good results.
Throttle bracket attachments
The throttle cable has been a bolt-on affair for 5 years, now. It doesn't change.
The line-pressure cable from the trans has to be at rest at idle and fully pulled at max throttle. You don't want to move the STOP lever to gauge where WOT is - you want to use the throttle pedal. Yes, you'll get 2 different results otherwise, because the throttle cable pulls thru some plastic bushing, whereas the STOP lever is hooked up directly, bypassing the plastic bushings.
The cruise control also needs to have no tension at idle and full pulled at WOT.
I used Lokar throttle cable ends to accomplish this. It's not the ideal setup to last 300k miles, I'm sure. But if I get 30k out of it, I'll be happy. To make it ideal, I'd add some stiffeners to the line pressure tab, reclock the cruise module to aim straight at the throttle bracket, rebuild the whole assembly with new bushings. Or better yet, throw the whole works in the trash and design something simple. But since the throttle lever must move backwards for emergency shutoff, it makes things extremely complicated.
I leave the throttle at rest and the cable at rest, and I draw the arc that the cable makes across the bracket. Then I repeat this with the cable and throttle at full extension (WOT). Where these 2 arcs overlap is where I drill the hole for the Lokar. The Lokar has tons of adjustment built into it, so you can fine tune everything. I did have to add some additional material, which I simply cut out on the plasma table and TIG'd on.
This is literally all I had to connect for the cruise and automatic trans to function. The ECU stayed in the vehicle, which controls cruise. Nothing else was needed (no cam or crank or TPS sensors).
When I engage cruise, I can let off the pedal quickly and feel the cruise module sucking in the slack. While this is happening, the speeds drops a bit. This won't be the case in my Tacoma since the throttle cable actually routes to the cruise module, which routes to the throttle. It'll be simpler, cheaper, and tighter/better.
The cooling system is very simple. I used the stock radiator. I used a single hose for the radiator Inlet and 2 hoses for the Outlet. I had custom thermostat housing fittings made to accommodate the ~1-3/8" hoses.
I've requested that ICT Billet makes a 1-3/8" coupler, but they haven't responded to me. Please ask them yourselves, and I'm sure they'll eventually do it. I'm using their 1-1/4" splicer, and it leaks if you don't have your hose clamps perfectly tightened.
I use my favorite 16" Spal fan: https://amzn.to/3X3Eah1
Tucked up into the far top LH corner to dodge the accessory pulleys (this pic isn't accurate - I had to move it all the way up). I had to attach it prior to installing the radiator.
I'll cover the fan controls in my wiring post.
Installing the radiator was tighter than a *****. I found the trans connections are compression fittings, and you could probably convert them to AN hoses, if you wished. I believe Jeeps AW4 cooler lines were actual pressure lines. Toyota did it super goofy and ran pressure lines about 8" off the trans, then ran 2' of low pressure rubber hose. The lines are on the low-pressure return side. But the chances for a leak are scary, as your trans would die a quick death if one popped off.
Anyway, I had to remove the RH compression fitting to get the rad in, as it wouldn't otherwise clear the AC compressor.
The overflow outlet is in a TERRIBLE location. I was lucky enough to find this perfect shaped hose somewhere on the 4Runner, to keep it out of the serpentine system.
Filtration is something I always get excited about for some reason, as if it's going to add 100hp somehow.
Oil is currently being sent thru a dual filter head. This unit leaks unless I tighten the filters with a filter wrench, so I do not recommend it. I had it though, so I'm running it. I run a standard 3/4-16 filter. Toyota has an "oversized" filter option for the 22R, which was what I gravitated towards on all my builds. I buy filters by the dozen when they're on sale. Look at this BS! This HP-2009 from 2019 is larger and cheaper than this 2022 version, which cost about $5 more.
I have since moved on from K&N oil filters, as Autozone no longer carries them anyway. Their 1" nuts were sure convenient, though. Now, I'll be using Wix for my oil filters.
The fuel filter is of course the Donaldson equivalent of the CAT 1R-0750, since the Donaldson has the water separator. I was running a CAT filter that had <500 miles on it, and the o-ring blew out!! I removed the filter, reinstalled the o-ring, drove 30 miles, and it BLEW OUT AGAIN! I threw the filter in the trash. The o-ring had swelled, probably from coming into contact with penetrating oil when I was replacing the prechamber. I've never seen that before, and hope I never do again. I'll stick with Donaldson from here on out on the fuel filters.
After witnessing chaos in my 855 Cummins, I've become an instant believe in coolant filtration. I'll try to make this long story short... I called Cummins/Fleetguard as well as the local-to-me Baldwin. Baldwin was much more knowledgable. I actually found a major typo on Fleetguard's website, falsely advertising that they had a full-flow coolant filter, which was in fact a by-pass filter. Baldwin is out of Kearney, Nebraska. Their engineer was quick to help me design a full-flow system for my 855 motors to get the huge chunks cleaned up in short order. For engines, like this 617, that are not heavily contaminated, a by-pass setup will work just fine.
To do this, you must install the filter between higher and lower pressure sources. The easiest/most common is before and after the heater core. You "T" the filter head into each line. Imagine an "H", and the filter is the middle of the "H". I simply put a "Y" in the heater hose outlet coming from the head, running it to the filter inlet (so much for that pretty 1-piece made-to-be hose 😢). I put a "Y" after the heater core outlet, routing the other side to the filter outlet. This allows coolant to flow thru the filter without impeding flow thru the heater core, and when the filter is plugged, nothing else will be affected. This also allows flow when the heater is off. The filter flows a max of 2GPM, and only 3% of the coolant passes thru it on each pass. According to Fleetguard, it will only take 4 hours of runtime to filter the majority of the system down. When the filter is not hot to the touch, this means it is plugged, and it's time to replace it. Otherwise, an annual filter change is a recommended service interval. I've seen these go several years without being changed, and while they still flowed, they began rusting and were a bear to remove. I also wonder how long the filter media can last without breaking down when left for years on end. When properly maintained, engine rebuilders say the inside of the coolant cavities on engines with coolant filters are shiny clean.
Here are the parts I used:
https://amzn.to/3EmWTMQ
https://amzn.to/3A3xeX9
https://amzn.to/3th6w9G
I'm getting very technical about designing a couple different air intake systems for several different specific vehicles/engines. I invested in some top quality equipment so I can measure the vacuum an air cleaner causes. 15" h2o is where I draw the line, to give me tolerance for a dirty filter.
I slapped on my cheap universal Spectre filter to get me up & running. I couldn't measure it's restriction with the plastic 90° elbow, so I ordered a cast 90° that I could weld a bung into for my gauge.
I'd assumed the Spectre was restrictive, so I ordered a massive 12" K&N - the biggest I could fit - but much to my surprise, the max vacuum I could pull with the Spectre was 4", even with being very dirty.
I'll return the 12" K&N in favor of something smaller, which will make building a cold air intake/water shield so much easier & better.
I've ordered a bit larger K&N filter to replace the Spectre. I'll update when it gets here. Going to build a box for it so it's a true CAI.
Modifying the fuel tank on these is pretty straight forward. Removing the tank and filler neck sucks, though.
There is a plastic shield that must be removed to get to the filler neck. I used a 7/16 socket on the backside of the plastic clips to release them. They are $19 at Toyota, and I haven't found a good universal replacement. In hind sight, I could've probably left all of this in place and modified it on the vehicle. Just disconnect the filler neck from the tank.
The filler neck restrictor, from what I could tell, just has to be beaten out to the best of your ability. Make sure to clean all debris out of the tube when you're done. I used an air chisel to open mine up.
To drop the tank, you'll have to pull the carpet up on the rear LH seat and unplug the harness going into the pump. You'll also want to reach in and pop the plastic retainer free, if you can. I destroyed mine form underneath - just another stupid automotive engineering oversite.
Then you can drop the tank. You'll want to drain 100% of its contents. Some had a drain plug, some didn't. Oh joy.
You'll want to remove the pump and rollover vent assembly.
I modify the vent by cutting the line, smashing it flat, and welding shut. Then, I leak test it. Reinstall. A new gasket is probably a good idea if you have the foresite.
The pump gets removed and replaced with either fuel hose or a piece of tubing, to draw fuel from the bottom of the tank. Cut the tip at a 60° angle to prevent the possibility of sucking against the bottom of the tank. It also helps prevent clogging if big debris gets in the tank, and makes for smoother fluid flow, according to FillRite. Mine got cut a bit short here... And I was out of hose. So I will be sure not to ever push this thing past the Fuel Light coming on. I've also done these to where I modified a pick-up sock screen to fit the hose, to retain the filtering and original drawing point.
I want to give my brain a break from wiring for a moment and talk about injectors. I had mine rebuilt by Vaughn Classic Specialties. Alex is a great guy and knows more about injectors than I ever want to. I had several leaks, and assumed it was the injector bodies. I eventually got all of the leaks stopped by replacing the return hoses. The best way to do this is either on a warm engine, or use a heat gun to heat up the injectors. Then, the hoses slide on properly. Doing it cold tends to create more leaks.
I sent the injectors off, anyway, as I want this thing in tip-top shape. He got them and pop tested them, and told me they were one of the top 3 sets he'd ever seen in his career. This made sense since this was the quickest starting OM617 I'd ever come across. But that made me pretty depressed after experiencing what I'm about to share....
I bought a used set of injectors, had them mailed to Alex to rebuild, so I could swap out and minimize downtime. He said my original injectors were better than the ones I was getting ready to install. Oh well - I figured I'm splitting hairs here. The first 4 swapped out without issue. The last prechamber washer WOULD NOT come out. I've since found a method that should remove almost any washer. But I destroyed my prechamber trying to get this one out.
Use a tapered punch that will wedge into the center hole. The friction should be enough to break any seize without harming the prechamber.
I had a ton of brown liquid in here, so I wanted to pull everything for inspection. After pulling the prechamber, I found even more brown sludge. I will say that it was good after all, that things happened the way they did, as I fear my head would have eventually rusted out and would have been totaled. I bought a new prechamber and installed without any issues. I will be making and selling prechamber removal tools after this ordeal, though, as it is a proprietary thread and the tools out there are insanely high.
I determined that the brown sludge likely came from water entering via the indexing slot in the head, that orients the prechamber to align with the glow plug hole. Filling this with RTV is probably a good idea if you're the type to wash your engine regularly. Or, make sure to run your engine up to temp immediately afterwards to evaporate any moisture that gets in there.
While I was in there, I did get a chance to use my new endoscope. I was able to see some awesome looking crosshatching still intact. And I made sure I got every last piece of debris vacuumed out to prevent destroying my engine. Had I stopped after I'd initially vacuumed and thought it was sufficient, I would've most definitely destroyed this cylinder/piston. I put the probe in and found several huge chunks of washer.
I also got to use the endoscope to find an obstruction in my fuel filler neck. I had plugged it to catch debris when I was modifying it. Apparently one of the several towels broke off when I removed it, which luckily just clogged the filler neck instead of going into the tank and clogging the pick-up tube. It paid itself off just with this first use!
https://amzn.to/3ElkxcN
Gauges Part 2
The critical gauges I always run in anything are:
-Oil Pressure (your engine's blood)
-Water Temp (to prevent blown headgaskets)
-Pyrometer (to prevent melted pistons)
-Boost (to prevent blown headgaskets)
-Tachometer (used for setting idle and getting good MPG by finding target RPM)
If I have an automatic, I also run a Trans Temp (see the Gauges Part 1 post).
These 96-04 have terrible gauge clusters. They don't even have a volt meter for crying out loud. I don't know what happened to SR5's having all the fixings, but these don't. In my opinion, every vehicle should have all of these gauges.
I decided to run Glow Shift gauges for this project, as AutoMeter quality has gone down the toilet, while their prices have sky-rocketed. I opted for the White Elite 10-color series. GS has so many more perks over AM. AM wants $10 for an LED bulb to change the backlight. GS has every color pre-installed, to change with a click of a button. AM has outdated wiring while GS includes a daisy-chain feature. GS also has many more features:
-Records your Peak value for you to reference at any time by pressing the Set button
-Offers flashing and beeping alarms for Hi and Low values that you set
-Can output a signal for said warnings, for you to run things like a larger warning light or trigger an engine shut-off solenoid, etc.
My only gripes about these GS gauges are that the White 10-Color don't have a Water Temp gauge, which is asinine to me since that is a basic, critical, fundamental gauge. And, they don't have backup batteries to remember your settings - so if you disconnect or drain the battery, you have to reprogram all of them. Not a huge deal, as it takes less than 2-3 minutes to do. People also complain about the brightness, and I tend to agree. They dim when your lights are turned on (if you connect the appropriate wire), but I find the White light to still be too bright at night. I wanted white to match my new gauge cluster backlight. I've found myself switching to Green at night. I will also say that the 2 color changing modes (1 blinks from 1 color to the next, the other slowly fades from 1 to the next) are idiotic and just add extra unnecessary clicks when changing between White & Green. I realize that's bold, but seriously, running a bright gauge that changes colors constantly is a hazard to the driver.
Lastly, none of their gauges are mechanical. Mechanical fits so well with Doomsday, and I hate sensors, but the benefits outweigh the cons in my opinion for this build.
Here are the 4 gauges daisy-chained together, so I only had to hook 1 wire up instead of 4, for each function. SOOOO much cleaner than an AM setup. I put them in a pod to make mounting simple for this cheap/quick build. They have every mount style you could imagine, and at great prices. I actually ditched this solid mount for an articulating pod setup, so I could individually aim each gauge towards my line of sight.
I reluctantly ended up using the Toyota Water Temp gauge, but it's working well, and I know the values after finding them in a Toyota manual, so it's not just a needle pointed at an arbitrary point.
Here, I've got the hood removed while I'm waiting for intercooler connections to show up. I wanted to test the IC in a best-case scenario, where it's getting full possible flow. If it doesn't work here, I'll know it's definitely too small to go under the hood. As you can tell by my gauges while cruising, it works excellently.