N62 Z3 Part 10: Finishing Wiring & Fabrication Preparation

Welcome to part 10... it's been a long time coming!

So the first thing to do was to get the the fuel pump in the car working. This is how it ran it to get it to start the first time, with the fuel pump powered directly. They aren't touching like it kind of looks like they are

This was really a super simple process after figuring out the wiring diagrams. That process took just a bit longer than it should have because the diagram for the N62 X5 fuel pump were labelled incorrectly. The diagram indicated that the fuel pump relay output is on the engine harness itself. As it ends up, it was not. When I found what the correct harness and pin was I realized this was actually related to that mystery IVM "power supply" wire I had troubles with earlier, when the IVM was wired wrong

On the N62 cars this power supply feeds a few things - e-box fan (which is how I eventually wired mine) and fuel pump relay among them. The Z3 powers this from the engine harness directly and there is a plug in the DME box which feeds to a fuse and then to the relay. So it was simply a matter of connecting one side of my meter to the fuse and probing the other side until I hit gold

And gold I did hit. Some of you may recognize this harness from earlier, especially you binge readers who read this all in one session. This red/white wire is the one that feeds to the fuel pump relay. I had previously ran a male plug into this harness to tap that green/white wire. So all I needed to do was crimp the corresponding terminals onto a length of wire and click it into the corresponding spot in the harness. Easy. No hodgepodgery, no cutting, no splicing. Just good ol' crimps, the way BMW intended

The e-box fan is currently unpowered (I de-pinned it's wire from the IVM to make room for the above wire). The e-box fan is DME controlled by ground though, so I should be able to give it any 12v power supply and it will work fine. I could also tap into line if I wanted to, just crimp a new wire with an extension going to the e-box fan positive. Not a big deal at all

With it all wired in, it's time for another start. I did not align the DME-EWS this time

It is running completely self-contained! This is really great because it means the fuel pump relay is now working AND the DME-EWS have been aligned successfully and it ran long enough for the "rolling codes" to align. Or whatever the term is. Basically the DME and EWS are best friends now. And the Valvetronic DME is just like their little weird... slave thing... yuck. I'm going to try to stop anthropomorphizing (I spelled that correctly the first time round, today is turning up all Aces for ol' Graham!) engine management computers now.

And, only 10 errors in the DME, all of which are accounted for

Also, I am not sure I have noted this before, but I think it's weird the N62 uses mechanical tensioners

Also, just *cough* a slightly related observation

E39 frame rail width, about 30"

E60 frame rail width, about 30"

E60 subframes bolt to E39's. I just can't shake the idea of an E39 wagon with a 4.8is drivetrain in it, including the 6 speed auto. Just seems so cool. Gonna finish this build first but I'm actively on the lookout now for E39 wagons to buy for that swap

Alright, back to this build...

So, what's next? Good question actually. I'm kind of still deciding. I was so focused on getting here that I wasn't even thinking of where to go next Obviously it needs fabrication work. Like, duh. But I'm trying to think of what else I should do before the engine comes back out again, if anything. I'll ponder it over the weekend and plan on taking the engine out early next week to start prepping everything for the fab work. I'm going to try to get everything done *except* the engine mounts, I want everything in place before those get made Have a feeling my VISA card will be burning pretty soon too - it's just about time to purchase the N62 refresh parts. I think I'll stick with the 4.4 in the Z3, but I will spend some time deciding that over the weekend as well

One important question has come up. Should I learn to weld and do 100% of this project myself?

Or plan B: basically buy my fabricator a Ferrari because jeeez this is gonna add up quickly

...I think I'm going to learn fabrication and welding myself as those are skills I am going to need going forward. In the meantime I threw the radiator core support in place to get an idea of how much room I have to work with

It's hard to get an idea of the perspective here but there is about 7-8" of clearance between the front accessories and the edge of the radiator support, which has everything but the radiator installed. It seems like there will be plenty of room to fit a large radiator and the intake system

So next up is a lot of stuff so I'm going to be writing down what I need to do here to organize it for myself. I also have a lot of customer work in at the shop at the moment so things are going rather slowly on my personal stuff - I am thinking of closing the shop to customer work again, because I really want to focus on this swap and future swaps. In fact, speaking of future swaps, I bought another engine...

It even came with a VAC dry sump, complete with reservoir!

For those who don't know, this is the BMW S62 V8 engine. It's a little hard to tell because it's currently disassembled but in my opinion it is the best BMW V8 ever made...

Anyways, I plan on putting this S62 on an engine stand and rebuilding it slowly to use for a future swap - most likely into a different Z3, maybe a coupe. Some of the S62 engine gaskets I need are backordered until April (its February 11 as of writing this) so I think it will be a slow process. It has a crank and pistons installed and the block is said to be good, I will double check that though. It came with ARP rod bearing bolts and a new set of rod bearings which is great

While I wait on parts for that, I have plenty to do with the N62 swap

The first thing I will need to do is set the engine height to establish the correct driveline angle

Once that is done, I will need to determine if the shift linkage will fit or if the transmission needs to be dropped down to allow for clearance. If it does need to be dropped down then I will have to re-adjust the engine height to set the driveline angle. I am hoping I can make it work with the transmission bolted in as it is now, as I don't want too much stress in the center support bearing

With the engine set at it's final height, I need to get the engine mounts made. To do that (I will get them outsourced for now) I first need to modify the subframe - it looks like the oil pan will just barely rub the rear 1" or so of the stock subframe. The oil pan is angled steeply here so I will try to match the subframe to this contour to maintain as much of the original subframe structure as possible

Then the subframe can be bolted into place and engine mounts can be fabricated

From there, I can work on the rest of the stuff in no particular order

Fabrication - Modify front subframe (after doing all of the above)

- Engine mounts

- Fill/plug the SAP ports in engine heads

- Clearance both frame rails for clearance (alternator/tensioner bolt)

- Driveshaft - thinking of a few options here but not sure on anything yet ...E60 front paired to E46 custom shortened rear? E60 front customized to have a Z3 style center spline joint? I think there are many ways to solve the driveshaft problem

- Shift linkage - stock E60 carrier and selector rod with the length modified should work fine

- Headers and steering shaft - this is the big one, my main concern is the driver's side header and in particular the clearance around the steering shaft. I have seen some people drop the steering shaft down the firewall ~5" or so, which seems a better solution to me than adding an extra U-joint in the system. I will need to investigate this further to see how things look once the engine is in place (*note from later on - it looks like dropping the steering shaft location down the firewall will cause interference at the chassis where the framerail meets the firewall

- Obviously after headers comes exhaust, I am thinking I will run an aftermarket Z3M rear section and then I will just need a custom fabricated mid-pipe from headers to the rear section

Cooling System

- Verify cooling system routing - first I need to just sit down and figure out what goes where on the N62. Most critically is knowing how many engine inlets/outlets there are and where they go

- Radiator - thinking I will start with a stock S54 radiator and run the N62 oil cooler lines to an S54 style oil cooler, like the stock S54 configuration

- Lower radiator hose - needs to be modified for the N62 coolant temp sensor

- Heater core hoses

- Expansion tank routing


- Fuel pump

- Manual pedal installation with lines and etc, as car is originally an automatic

- Clean up wiring a little bit - re-route electric pedal and ignition wire through firewall

- Remove stock accelerator pedal and install electronic pedal

- Diff swap - maybe a complete rear-end swap? I have a spare 3.0 rear-end which is quite a bit beefier than the stock 2.3 stuff, so I may try to find some time to install that, although I could just swap the diff for a less crazy ratio (stock is 4.10) and swap to 3.0 stuff later, depending on how long the rest of the stuff takes

- Paint engine bay with engine out


- Positive engine harness cable - run a positive cable to the starter and the alternator from the battery (currently the starter has jumper cables powering it directly)

- Intake

- Refresh - valve stem seals, coolant transfer pipe, alternator bracket oil gasket, engine gaskets, clutch kit

It's a lot - but when I write it all down, it actually feels like less than it did when it was just floating around in my head... just need to start at step one and start looking at the driveline angle and then checking shift linkage clearance

I am sure though that there are as many things I am forgetting that are not on the list, as there are things on the list. I think these are the big things though

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Here is an S62 on an engine stand

So the beginning of the fabrication began with one last test start... I just can't believe this thing runs sometimes. Started right up. So, OK... let's yank the engine out

Then I decided to go ahead and drop the front suspension and subframe out, since I know where everything is sitting in relation to one another and where to start fabricating things. In theory the next engine installation could be the last one, heck I didn't even have to take it out this time, but it makes things easier and it was out very quickly

I also removed the trans tunnel insulation, the rest of the firewall insulation, some of the heatshields, the A/C line and the brake booster/master

So the next step is modifying the front subframe, then reinstalling the engine, determining the driveline angle and then fabricating engine mounts. At that point, the engine will be removed, steering rack installed to the subframe and steering linkage to the chassis and then that will be test fitted with the engine/headers

The N62 wasn't the only V8 I worked on today for anybody curious about S62 stuff... I will likely move that into it's own place later but will put some of it here for now


I unwrapped it and inspected it for the first time today. When I first opened it up there was a lot of dirt along the cylinder walls, what ended up - I think - being broken down carbon build up from around the ridge. It was pretty easy to clean out, but was mildly coarse, so I was as careful as I could to remove as much as possible before rotating the engine

First thing I did was remove as much as I could with an oiled rag. Then I used a shop vac to get the bits that were caught above the piston ring between the piston and the cylinder wall. Once I was satisfied that I had as much as possible removed, I dripped oil onto the rings and generously lubricated the cylinder walls before turning the engine over just a little bit. Just that little bit revealed a lot more gunk. I would wipe again, lubricate the walls again, rotate again and each time this would reveal less gunk. I have a feeling there is some crud trapped in the rings so I dripped a generous amount of oil into the cylinders when I stored it after working on it today and will repeat this process

I discovered the likely reason why it was torn down (very bad rod slap on cylinder 4) and verified all the cylinder hones looked good. The one below was the worse by far visually, but couldn't be felt by a fingernail

There was a different cylinder that if I really, really dug my nail into it I could just barely catch it. It didn't look like much in a picture and was just one isolated tiny scratch. Almost all of the other cylinders pretty much looked like new, so I think I am going to run it without honing it

The below did have me a little concerned though, I noticed a few minor imperfections across the deck surface. A few of those are pictured in the image to the left. These are likely the results of being stored. The only one that goes into a combustion chamber is the one in the very center of the picture. It is a very thin scratch, extending almost between two cylinders. I am thinking of several ways to address this and the other minor imperfections currently

In the meantime I also cleaned the pistons a little bit... (the right one in the original, uncleaned state). I did so by rotating each piston I was working on to TDC, so it was sitting just proud of the deck (shown in the following image), flipping the engine upside down so that any dirt that came off would fall to the ground instead of into the bore and then just scraping with a plastic scraper. Whatever buildup was on there came right off, I assume because it had been stored properly and well oiled and the detergents slowly ate away the carbon buildup over time. You can also see a good example of the other cylinder walls in the below image and how nice they look

Pour some TWS 10w60 for all the plastic scrapers that gave their lives for clean S62 pistons

The bores were then oiled again, the piston tops were oiled, the engine was rotated over a few times, the bores were then re-oiled (because dang those piston rings actually seem to scavenge pretty effectively) and a rudimentary temporary storage device was conceived...

Next step for the S62 is to address the deck surface and get the heads ready to install! But the heads won't be ready for assembly until probably March, possibly April, due to parts availability. Parts are on order though. So, full steam ahead on the N62 then!


The next day I made some more progress on the Z3...

First thing was to take the pedals out. Look Ma, no pedals!

I've been waiting to make that joke that since about when I first started this swap and I realized at some point I would have all the pedals removed from the car at the same time. So with that, I've reached a pointless personal milestone

Next was to remove the throttle cable and pop out the little grommets for the clutch hydraulics

From the engine bay side... (the upper grommet does get popped out too, for anyone wondering)

And this little X will be drilled... this location and a spot directly across it. The reason for all this is to re-route the pedal wires from the engine bay to where they belong in the footwell

So... I still feel dumb for having cut out this bit from the firewall. I will be repairing that soon, I will talk about that a bit later. But it did make routing these wires a lot easier - as you can see they run into the windshield wiper cowl area

I was very paranoid they would get caught in the wiper mechanism so I was careful to secure the wire to the plastic at several points here, especially close to the motor

And then I ran some grommets to clean everything up...

And the finished product below... looks nice as far as the grommets and everything but overall its a little silly to be honest? I may end up just opening it up a little bit (to prevent the wire from snagging if it ever needs to be pulled through) and welding a "pocket" around it. But then I start to worry about scope creep, because I was also noticing while doing something later that boy, this chassis could really benefit from being continuously seam welded from the looks of it... and it would look really cool if it was wire tucked and shaved wouldn't it?

Back inside, the wire lengths looked like they were just the right length... a little close for my comfort even though I thought I cut them very generously! I did do a little concentric twisting on the wires though, which used more wire, so maybe that's why

And electronic pedal mocked up in place... it looks like this one may work, I will get the bracket out of one of my parts cars and see about installing it and finalizing that in place

I also tried to install the clutch pedal. I think I had mentioned many moons ago that I had a spare clutch pedal assembly I had bought and never used. Well I dusted it off today and was very disappointed

It looks like someone got halfway through swapping their pedal assembly and gave up - the pedals were correct, but the hardware was not correct for the manual assembly - notably the bolt for the slave was too short/missing and various bushings and clips were missing. That wouldn't be so annoying if I didn't pay for a complete assembly (like, 2 years ago? haha). Oh well. I already have a replacement ordered. Will be nice to wrap the pedal stuff up soon

Then I went ahead and worked on those transmission tunnel studs used to mount the insulation. You may be able to tell the top two are bent a little bit, due to the transmission hitting them. Maybe it will fit even nicer now with those removed - occasionally it did seem to snag on something I couldn't see

This was just done with my rotary tool, I will probably buy a little finger grinder to finish those off and prep for a nice primer job, even though this area will eventually be covered in heat rejection tape

Talked to my friend who will be helping me with the welding aspect of the fabrication, he was out of gas today but this next week we will work on the subframe. I'm also going to get that firewall piece welded back in - I need to start thinking about paint pretty soon, which means finalizing all the stuff like that

The next time I worked on the car I cleaned it, which is a critical part of any paint job... I will be doing many more cleaning steps before laying down any more paint but I also decided on a paint scheme...

I have cleaned this car before but it sat outside for a little awhile during some inclement weather and definitely picked up the worst of it. Believe it or not - it had already been washed with my pressure washer in the below pictures. From here on out it will only be washed by hand so I also went ahead and did some masking

I ran out of masking tape and will need to go back with some bags and aluminum foil to finish covering rest of it - but most of it is masked at this point - obviously I will need to find a way to prop those brake lines away from the chassis while spraying but happy with where it's at so far. I did go ahead and pull back out the throttle cable I routed yesterday as well and the DME box is now resting on a chair so it isn't putting tension on the wires while it's out of the engine bay

Then I wet some rags with water and ran over the surface along with a little elbow grease to lift up that embedded dirt. Next I sprayed liberally with normal engine degreaser, being very careful to avoid any masked areas

Mmm. Caustic

When rubbing down with the rags, the rag picks up plenty of degreaser so any areas not sprayed directly will still see some degreaser. The whole engine bay will eventually see this process repeated multiple times before painting, but only the first time is really visually interesting to look at. Eventually the last clean (or two, depending on my fastidiousness that day) is with a special wax/grease remover specially meant for pre-paint prep - but the surface will be scotchbrited and prepped before then. Below is where I left off today. There was a ton of grease that came off that passenger side frame rail...

I didn't get a before area of here specifically but there was a ton of grime here before...

Oh and the color choice for those wondering...

I'm going for satin black in the engine bay and Techno Violet on the body. I waffled back and forth on a lot of colors, a lot of different options... when I thought of that color combo, the above car popped into my head which is a muscle car and color combo I have always loved. Not to mention I love the black accents Current plan is I will paint the engine bay myself (if that wasn't already apparent) but then outsource the Techno Violet paint to a professional. Fabricator came through the next day to help me with the subframe, on to Part 11!