BimmerTim's Tacoma Build (tdi swap) and Trip Reports

That's what they make JB weld for

 

True enough. You just have to apply it after the welding, but before the painting...

 

Loving this thread dude. Keep it up my man.

 

The oil pan is finally done. Like, done done. After I finished welding the inside I took the recommendation to fill it with water to test for leaks.



I didn’t think there would be, since I welded inside and out, but I found 3 very small leaks that I had to fix. Rather than just re-melt I ground the weld out where the leak was and just re-welded the areas.

With the engine back out and the diff re-installed I test fit the pan in the truck for the first time. It’s a little closer to one tab on the diff than I would like, but it really does fit as intended.













Here is the ear on the diff that is closer than I would like. The pan will end up being slightly higher than shown. I also have a diff drop kit that would lower the diff by about 3/4" where the ear is. I’m going to hold off on the diff drop until the pan and engine are back in together to check final clearance.



Before I can put the pan on I need to build the new oil pickup tube. It went pretty smoothly right up until I decided to add a small brace. I ran out of 1/16” filler rod, so I was trying to use 3/32” filler, which got the thin bracket too hot and it cracked. Then I added some additional support and tried to minimize the filler rod usage. At the end of the day it will work fine.







Before I put the engine back in again I wrapped up the clutch line to the slave cylinder. When I bought the adapter kit they only had the option for a W56 bellhousing, which moves the clutch slave to the passenger side.







Engine went back in at this point so I can start on the exhaust, intake, and heat core lines. I also made an super accurate mock up of my radiator/intercooler setup. They will end up being side-by-side. I have the intercooler core, but I’m waiting for the radiator to arrive before I start.



In one of my previous SendCutSend orders I had a thick downpipe flange made. The factory downpipe is pretty small, but so is the outlet of the turbo. I started with just a simple transition from 2” to 2.5” for the rest of the exhaust.





There’s a decent amount of room for the downpipe, but I want to get it as far away from the starter and clutch slave as I can to give them the best chance of survival. With the first few pieces in place where I want them to stay I welded those full out.





I ordered the super thick turbo flange so that I could smooth out the transition from 1.75” turbo outlet to the first piece of pipe that is 2” OD. I ground the transition out with a die grinder and burr bit then smoothed it out with a flap wheel drum, then tig’d the inside of the flange and pipe.



Bit by bit I measure, tack, test fit, and repeat until the exhaust lands just where you want it.







And then a wild downpipe appears…



I wanted to make sure I could get the downpipe out easily, as I think it’ll need to come out to do a starter, which is something I had to do on the Tacoma on the trail a few years ago. I also wanted to keep a flex pipe in there to minimize stresses on the downpipe.

The goal was to fit the new muffler in the same space as the original cat. It’s a tight fit, but it places the muffler above the trans cross-brace and keeps the rest of the exhaust simple and able to be tucked above the bottom of the frame.



Next up is the air intake piping. There were only two things I wanted to include; A factory airbox and an integrated MAF flange. I’ve taken a few trips now where I needed to replace the air filter and trying to find the correct size cone filter was tough. Having a factory airbox will all but guarantee any parts store will have one. The 2.7L airbox is clamshell design, so piping needs to be removed to pull the filter out, but the 3.4L V6 airbox has a little flap that lets you pull the filter without tools. The only problem is that the MAF housing is integrated into the airbox, so I had to cut it off and make a little adapter.





For the piping I started at the airbox and just tried different angle couplers and aluminum piping. I liked this combo of 60deg coupler and 45deg aluminum pipe, but it pushed the piping too close to the turbo.







In the end it was a simple 90deg coupler and straight pipe. It ends up pretty close to the high pressure A/C line, but it should be enough clearance not to cause issues.







I added a honeycomb flow straightener pre-MAF.





Then cut the hole and welded on the MAF flange.











I picked up this little power steering reservoir bracket that is used on E46s to relocate the res.



I finally found an EGR and ASV delete pipe for the PD150 manifold I bought.



That’s all for now. Next up should be the heater piping completed, clutch and flywheel install, and final engine install.

 

Nice progress! FYI on the diff drop, it's not a true "drop". It sort of rotates it forward and down a bit since you can't drop the rear mount stud.

You should wrap the down pipe in heat wrap to further protect the starter. That or some sort of heat shield between the two.

 

Thanks.

Yeah, luckily, the tab is near the front of the diff so it should drop nearly the full inch. I'd still prefer not to run the drop if I don't need to since it changes the pinon angle.

I want to do both for the downpipe. I have header wrap ready for when I get the downpipe fully welded out. I haven't figured out what to do for a shield yet, but it's on my to-do list.

 

Pretty productive weekend. I started by finishing up the welding on the downpipe. Here it is out of the truck so it’s a little easier to see.





Then I baked some engine mount brackets.





Next up was wrapping up coolant connections for the heater core. Here you can see where the heater core connections naturally land relative to the existing flanges.



First connection is the return line that goes into the back of the water pump. I bought a new hard pipe to start with, because the original one was pretty rusty. I cut it before it turns behind the head and remade the piping to turn away from the head and land where the hose wants to sit in the engine bay.





Then on to the heater feed line. I started with an Audi A4 1.8t aluminum flange for the rear of the head.



This flange has a flange where another water neck bolts on for the heater, but it faces straight back toward the firewall in my case. Initially I had a couple of flange plates made that I was planning to add a pipe and nipple to, so that I could retain the bolt on flange. That would keep the water housing unmodified and easily replaceable. However, there really wasn’t enough space to the firewall, so I ended up modifying the water housing itself… It is aluminum, so it shouldn’t be a part that needs replacing, and I really hope it doesn’t bite me. Worst case, I do have a plastic housing that could be installed in an emergency, but it would bypass the heater.

For the modifications, I chopped the water neck flange off and filled the hole, then I machined a piece of 3/4” aluminum bar to have a 16mm nipple on the end. I welded and tried to blend that nipple pipe to the top of the water housing and drilled through at the very end. I waited to drill the bar out, so that I could bevel the weld area and have the most penetration possible.





I prepped the water flange and the thermostat housing for powdercoating, but I ran out of powder, so that will be next week-ish.



I also replaced the rear main seal and bolted the oil pickup tube and oil pan on for good. I didn’t grab a pic of it for some reason, though.

 

I have been working on this pretty regularly, but mostly not interesting low visual appeal parts; New diff and trans seals, rebuilding and reinstalling axles, etc.

Some of the more notable items.

I ordered a custom radiator in April with an eta of 3-4 weeks. 10 weeks into waiting they were still telling me another 2-3 weeks, so I canceled my order. The plan is now to build my own. I found that OG Honda Civic half radiators have a close enough core size to what I need that I’ll be working off of that. I found the cheapest possible 4-core civic radiator to Frankenstein.



I started with a rough idea and layout of what I wanted. Intercooler on the passenger side, radiator on the driver side.



I refined until I had an idea I could actually fabricate. The green is the final radiator, the red is the final intercooler, and the yellow is a frame with the same dimensions as the stock radiator that both can mount to in the factory location.



I “needed” both the inlet and outlet on the same side of the radiator, so I added an internal baffle to direct the inlet flow to the passenger side of the radiator before it flows diagonally through the core to the outlet on the drivers side. The inlet/outlet/bung locations are being fabbed with 1/8” holes in their place to make the parts more rigid for bending. I’ll cut the final holes once the parts are here.



The intercooler is a similar design except that the internal baffles just help to guide the air through the cooler.



The radiator and intercooler are bolted to the yellow frame via threaded standoffs welded to the face of the end tanks. To make sure the standoffs are in the perfect location and to aid in the yellow frame assembly I designed a little assembly jig as well.



Part should be here for the rad and intercooler right after the 4th weekend.

This has been done for a bit, but I adapted the high-pressure power steering line to -6an and made up a high-pressure line with Earl’s PS fittings and line.



Next I gusseted my uprights, reinstalled the tubular upper arms, and replaced the front wheel bearings and seals. I have everything on the way for a Tundra brake upgrade too, but I’ll probably wait until after the first test drive to minimize changes.





I didn’t like that the adapter plate had a mix of metric and standard hardware, nor did I like that the hardware that came with was not even high enough grade to be torqued to factory specs. So, I drilled out the mounting holes and used Time-Serts to adapt to all M12 hardware.



I also wanted to run flanged hardware, so I machined flats and clearanced the bellhousing where needed.



I had to find an M11x1.25 tap before I could install the flywheel as the adapter was a little crunchy and I wanted to make sure everything was properly torqued. With that I was able to install the flywheel and clutch to the engine for the first time.



This is a stock 22r clutch, so I’m guessing I’ll need to upgrade as soon as I add power to the tdi. It should do for now, though. I final test fit the bellhousing and better hardware.



The next time the motor goes in should be the last before first start, which is pretty exciting.

On to wiring. I really like to fully understand things, so I reverse engineered the tdi harness. I finished trimming and depinning what I didn’t need and am at the point where power and ground should be enough to start the engine.



I’ve also taken it to the next level by putting together full harness documentation, including pinouts for every plug and finding part numbers and vendors (DigiKey) for all of the connectors, pins, and seals.





I’m doing this mostly because the harness is old, has been flexed and messed with quite a lot, and essentially none of the wire runs are the correct length. So, instead of just cutting up and making this harness work, I’m planning to ultimately build my own brand new harness from scratch.

I have a lot of the final parts on the way right now, so I think the next update will be a pretty good one. We’ll see, though.

 

Really stellar work. Great attention to detail

 

Big thanks for documenting your process!

 

Thanks. It feels like slow progress, because I want it running now so I can use it, but it's been just over 4 months since I actually dig into it.

Any of the info you see I can provide, even part files, drawings, etc.

 

Excellent thread and build. Great trips and info. Keep up the good work.

 

https://youtube.com/shorts/eNh2kZkabOQ?feature=share

 

My wiring worked. Now to clean it all up and get it routed properly.

 

Lots of progress here.

I ordered a new shifter bushing a long time ago and decided to swap it out before I refill the trans. Glad I did, because it was GONE and bits fell into the trans when I pulled the shifter out.









I also added this little brace to the downpipe, wrapped the downpipe, and reinstalled for the last time.



Intercooler parts finally showed up to, so I got to work on that. The end tanks fit up perfectly.





End tanks welded on. I also welded up the corner seams and smoothed them out.





The inside has the deflector plates stitched in as well.



Then I added the inlet/outlet fittings and the port for the MAP sensor.





Radiator parts showed up too. This was a little more of a pain in the butt as I found a hole in the first radiator I was sent, so I had to order a second. That one was a bit better, so I cut the original end tanks off and test fit my redesigned end tanks.





Then end tanks get welded on. I’m not sure what the core material is, but it welded sooooo bad. When I pressure tested it I found so many pinhole leaks I needed to grind and re-weld.







The fittings are for a drain and a temp switch for the fan.

To mount the intercooler and radiator in the truck I also made this adapter bracket to mount to the OEM radiator mounting locations. I started by bolting all of the parts to a jig.





Once tacked together I can remove the jig, weld it out, and add fasteners.





I had to make the threaded standoffs for mounting the radiator and intercooler to the adapter bracket then weld them on. With those added I was able to mount the radiator and intercooler into the truck.







Now I was able to start planning intercooler hoses and radiator hoses.

Lower intercooler hose.





Upper intercooler hose and rad fan and shroud.





And here’s where we stand today. Intercooler totally plumbed. Radiator totally plumbed, pressure tested, and full system pressure tested.

 

I'll have a real update soon, but for now...

 

A/C. We’re gonna keep it around.

I started by 3D scanning the side of the block, the A/C compressor, and the VW Passat A/C bracket. I tossed those into CAD and started messing around with mounting and tensioning options.





I ended up with an adapter bracket similar to what Jimbote had mentioned doing. Simply adapts the Tacoma compressor to the VW bracket.



Had the adapter plate made up at SendCutSend. To keep the threads from getting all messed up I inserted Timeserts to the mounting bosses.



Luckily it fit. So did the compressor…





I did have to sort out a different compressor fitting flange. The 4cyl and 6cyl Tacoma versions have the fittings on the side, which would get close to the frame and/or the boost pipe. I did extensive googlefu and found that a John Deere tractor uses the same compressor and the fitting flange discharges to the top with standard fittings. I ordered a few different fitting orientations and new high and low pressure line.



It all worked out pretty well, but getting the old fittings and line off of the Tacoma hard lines was a bit obnoxious, but it all worked out. I was able to pull vacuum and fill the system and it blows nice cold air.

Time to wrap up the power steering. Previously I had shown that I adapter the VW power steering pump and the steering rack to -6 AN.



I also used a BMW E30 power steering reservoir clamped to the oil filter housing with a bracket designed for E46 race cars.



The last bit to finalize was the power steering cooler. I was planning to use the Tacoma cooler, but I bent it. I also never replaced the frame brace that was ripped off by a deer, so I’ll get two birds stoned at once here. Into CAD!

I whipped up a u-shaped brace with some holes for air flow that a generic cooler fits in perfectly.





Got it made up at SendCutSend out of 1/8” chromoly and welded it onto the frame and the cooler fit mint.







Painted up the brace, final mounted the cooler and plumbed it in. Nice and low profile.



I made this super special tool to bleed the power steering without the engine running. It worked surprisingly well.



I need a throttle pedal, so let’s take a stab at it.

Like normal I 3D scanned the Tacoma floor in the cab and tossed it into CAD.



I loaned out my original mk4 pedal and the replacement I got back ended up being from a Euro A4 tdi. This turned out to be advantageous, because the pedal is removable from the sensor unit.



Adapting the sensor portion into the truck was fairly straightforward, except that the pivot point had to move up. This ended up not being a big deal, but it could have messed with pedal feel or placement or the ability to go to 100% throttle. This wasn’t the case here and it all worked out.



The adapter plate is just a simple plate with a very slight bent at one end that the pedal sensor bolts to and then the adapter bolts right into the truck.





There wasn’t a lot of room between the pivot shaft and the HVAC, so I had to bend the new rod in a kind of strange way. But the pedal placement and throw is perfect.





Potato

 

I should probably figure out the fuel system and maybe not keep running it on a Gatorade bottle filled with diesel and Marvel Mystery Oil…



As you can see in the prior picture and this one, I made a little mounting bracket for the OG mk4 fuel filter to sit in the engine bay.



On the tank side I started by using my engine hoist to pull the box and toper all in one.



That’s a lot of rust…



I didn’t take pictures, because it was so frustrating to have bought this in Seattle, didn’t drive it in winter, and still have this much rust. Even if it was mostly surface rust. In any case, for the frame I wire wheeled and sanded all of the rust off the frame behind the cab. I then used Ospho rust converter, which turns iron oxide to iron sulfate. Then a coat of Eastwood rust encapsulator. Topped off with semi-gloss black and satin clear.

The back of the cab was even more disappointing. As I was scraping and removing all of the loose rust I found the seam sealer just peeling off in large sections exposing what appeared to be hand grinding/sanding marks and bare metal. Red Flag! A little more inspection and pulling the rear interior out it became pretty clear that the rear panel had bee replaced, poorly, some years ago…

I had previously pulled the rear trim out to add some sound deadening and paid no mind at the time, but here you can see that the rear panel is all black, where the adjacent panels are grey. This is telltale that the black panel is a replacement.



While I was in there I added a layer of tar sound deadener and a foam layer over the top inside both of the extended cab pockets behind the speakers.



In my frustration I did not take pictures of repairing the rear of the cab, but the process was similar to the frame, with the exception of adding seam sealer between the rust encapsulator and black paint. I also used gloss black and a 2-part 2k clear. You can’t see this seam with the box on, so I wasn’t super concerned with blending or anything, but now it should keep it from rusting again.

Before pulling the fuel sending unit I jumpered the fuel pump and pumped all of the remaining gas into my daily. With the sending unit out I spent a decent amount of time getting the last bit of gas out, cleaning up any debris, and drying the tank out before dumping in a few gallons of diesel.



I removed the fuel pump from the fuel sending unit and just added a bit of submersible fuel line to reach the bottom of the tank.



To get the diesel pump nozzle to fit I had to make the filler whole a bit larger. The flap does fit quite right anymore, but it really doesn’t matter.



I lastly ordered a green diesel fuel cap to remind myself…



Box and topper back on without much drama it was time to wrap up the wiring. I started in the engine bay. You’ve seen the chaos pics of the wiring all over the place, but I took the wiring from each sensor on the trans and engine and heat shrink loomed it and labeled it. Where there were loom joints I used adhesive heat shrink to keep it as water tight as I could.





I routed everything around and up through the factory boot on the firewall. I used silicone/fiberglass heat sleeving behind the head, but that is about the only place.



On the inside I mounted the VW ecu in the same place as the OG ecu. I also did a TON of research all over and found new pins and seals for every plug on the VW and Toyota harnesses, so I was able to cut and re-pin every wire so they are perfect length. It was also so painful and tedious.





There is only one spot where the VW and Toyota interface, and it’s called the IK2 plug, located just above the glovebox. I did use three of the VW colored body plugs to have a termination near the ECU for the throttle pedal, cruise control, and the 109 relay.



I do still have a few things with wiring to finish and tidy. I ran new wires for the glow plug relay from the ecu out to the Toyota fuse box under the hood, but I haven’t terminated them at either end yet. I’m planning to use an unused fuse in the Toyota fuse box for the glow plugs as well. I need to make new ground cables. I also need to actually get the cruise working. Lastly, I just need to wrap the wiring in the cabin with the VW cloth tape to prevent chaffing.

Otherwise, it’s done for all intents and purposes. I’ve been driving it for about the last two weeks or so and have put nearly 300 miles on it. There is some maintenance stuff to do to the engine now that it runs and drives as well. The injection pump is loud and the nozzles have 278k miles on them, so I’m nearly certain it has to do with that. I’ll be doing a timing belt shortly, but that will entail finding a way to find TDC, since I don’t have a factory flywheel or marks. I also want to inspect the cam condition to see if I should replace it while I have the timing apart.

Once it’s good and reliable I do plan to upgrade the turbo, injectors, and a tune. I will have a permanent CEL until I do a tune since I deleted the EGR and ASV. I don’t currently have any other codes, which is pretty amazing.



If you have any questions or want to see pics of anything specific, let me know.

 

Another note on the truck and swap. I always thought the 3rz was super underpowered from age and general not goodness. But with the swap up and running it still feels much slower than I expected. I know it's larger than a golf, but it doesn't weigh that much more. When I bought the truck it had 31s on it, I now have 33s that measure almost 34 on it now. There is certainly a difference in pickup between the two, but I didn't really think about it when the 3rz was there. I checked my door sticker and validated on the intertubes that I currently have 3.58 gears. Boooooooo.

It makes all the sense in the world why 5th gear is and has always been useless. So, I'm thinking it might be time for a regear. Since I do drive this all over the country I want to keep rpms on the highway reasonable. To me, 4.30 would be good and would keep my rpms around 2750 @80mph, but I can only find a 4.30 rear gear. The lowest front/rear set I can find is 4.56, which would put me just shy of 3000 rpm @80mph. I did a little testing in 4th to see what 3000 rpm felt/sounded like at speed and it really wasn't too bad. So I think I might go down that road this winter.

 

lol doing an engine swap to then realize you only needed a regear

4.56 would be a great improvement. I'm glad I went with my 4.88's. They helped with the underwhelming power of the 3rz a lot. my truck originally came with the 4.30's and it wasn't bad at all. Only reason to change it really was the desire for lockers and to have better gearing for carrying more weight.