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.
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.