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 will come back to edit this post once I've figured it all out. But for now, here's where I'm at with the PCV and catch can... I want to run a catch can and an exhaust e-vac. My experience with catch cans has been they're too restrictive by themselves, so you must add a vacuum supply to them to facilitate flow from the crankcase. If not, the crankcase pressure builds up and blows oil out any possible place, usually starting with the turbo, oil fill cap, and dipstick.
I ordered a $15 e-vac kit from ebay. Got it installed - it just blows exhaust out. Sent it back and got a refund, thankfully. I determined it was only cut at a 25° angle. Supposedly these need to be at 45°.
I ordered one off Summit for $25 that's supposedly made by Holley. It's got a 45° cut. Heck, the welds over the old hole looked even better. But it also just blows exhaust out. This is regardless of RPM. I think I need to place it further downstream in the exhaust. I can't find any info about this. And the stupid part doesn't even have instructions. I've just plugged it for now and am running my PCV hose to the ground.
The minimum hose size you can run for the PCV is 5/8. I just use heater hose and a barbed 5/8 coupler to meet the factory 90° elbow. The e-vac needs a check valve to prevent pressurizing the crankcase. These come standard with 5/8" hose barbs, which is convenient. Running the PCV to the ground will drop small drips of oil occasionally, and will emit smoke - so if you want a clean looking/running rig and/or can't have oil drips, then you'll need to make a catch can work. Running the PCV to the turbo inlet will cake your intake/turbo with oil and is a horrible idea!!
As long as we're on the donwpipe, let's address the whole exhaust system. I ran a 3" turbo-back system. I would not recommend this unless you have the room. For future 96-04 swaps, I'll use a 2.5" downpipe. I had to use a BFH to clearance the DP from the starter, trans dipstick, and swaybar bracket. I used my own 2.5" to 79mm Holset v-band coupler, a cheapo amazon stainless 90° (you want 16ga, not 18ga), followed by a generic steel 90° from Summit, and a v-band at the end. This is my "downpipe". The rest of the exhaust is 2 pieces.
I welded a cheapo amazon flex pipe (highly discourage these, despite how enticing $16 appears) to a straight piece of 3" pipe roughly 7' long. I only had to make 1 cut in the middle to angle it about 8°. This is the middle piece.
The rear is from a 2000's 6.0L 2500 Chevy. It's supposed to be 3", but it's more like 2.75". But it has a great bend to clear the axle and point the exhaust out in the general direction you want it. I will eventually cut the tailpipe and re-aim it to look a lot better. I coupled the 6.0L tailpipe to the intermediate pipe with a slip-over clamp after having my local exhaust shop flare the 6.0L pipe. I think a Duramax tailpipe would work better. But they're Ø3.25".
The sound of an OM617 is very uniquely its own. It's not a Cummins; it's not an International; it's not a CAT. The closest thing I can think of is a Detroit. Keep this in mind when building your exhaust system:
-2.5" will support more power than this engine will make
-The larger the pipe, the lower the tone
-The smaller the pipe, the louder the exhaust
-3" is generally a PITA to snake by the starter
-These OM617's have an annoyingly loud idle heard from the motor (not exhaust)
I love how this one sounds in the cab (hate how loud it is by the hood). I need to do a drive-by, as I'm thinking the tailpipe probably doesn't sound that great blasting past you on the highway (or maybe it does?). Tailpipe idle sounds great tho. The open air filter and 3" system generates more turbo noise than exhaust, from what I can hear inside while driving. All I hear is turbo noises 😍