N62 Z3 Part 26: The Part Where I Get To Finally Enjoy It

I started it after all that rear suspension work and let it idle a bit and it started smoking again... so I decided to pull the valve cover to check the stem seals. Everyone and their brother seems to think that it's always the seals when an N62 smokes so I had to at least rule it out


Nothing really jumped out at me as "oh that's the problem" as everything seemed seated correctly and the area they were seated in was clean and they were all installed properly

Cylinder 7's spark plug was the only oily one and the volume of smoke seems like only one (or two? wouldn't it be great if I did cyl 7 but 8 was the issue... lol) cylinder is causing the smoking, so I removed all the seals on cylinder 7 intake and exhaust valves and cleaned the seating area thoroughly. It was pretty clean before I got there but I just wanted to double check

One keeper got lost and I spent about 40 minutes looking for it, was a bit of a nightmare to be honest. It actually got lost twice. I found it pretty early on and flicked it out of the area it was stuck in (between the spring and part of the eccentric cam assembly) with a ziptie. Then I couldn't find where it went...


Ended up using a shop vac on "blow" mode and after blowing out all under the eccentric cam area, I saw it fly out and rest on one of exhaust springs

This keeper is the 2022 Hide and Seek Champion

Buttoned it all up... and great news, it's still smoking

Actually, it's awful news. The only good news was discovering I can indeed do valve cover gasket jobs with the engine in place


My current working theory is that the way this CCV is setup will always make it ingest more oil on bank 2. So perhaps it's entire life bank 2 has ingested more oil and maybe the smoking is just a lot of crud from the SAP system that I plugged, which is finding it's way into the exhaust as the engine reaches operating temp and letting it sloop out into the exhaust. In additional to a constant puff of smoke, the exhaust is literally sputtering oil out of the header. There becomes a little spray pattern on the ground under the header and then after turning the engine off it'll drip a couple drops of oil out


Well all that may have been for naught. It ends up it was overfilled with oil which a BMW service bulletin says can cause smoking on these motors. It says to fill to the "low" level when the engine is cold, so I drained some oil out and ripped it around at full throttle for a few minutes. At first some puffs of smoke came out, but gradually they became smaller and smaller, I continued to drive it hard ~5 minutes past the last observed smoking, then let it idle and did not observe any smoking at that time. I am hoping this concludes the smoking saga

When I checked the oil level while hot it was at the full mark, so I think that is all good. I will drive it a bit more soon, probably to the gas station, then the emissions testing place if the readiness codes indicate it is ready. Then maybe I can start focusing on cosmetics!


First of hopefully many trips to the gas station

The expansion tank started leaking (I had previously JB Welded it as a temporary measure) so the replacement came in today and I got it installed. Pressure testing it and "cold bleeding" it

The rear is a work in progress which is why I've only photographed this angle so far lol


The next drive I took it out specifically to monitor the coolant temps as when looking at it after some previous drives I noticed both radiator hoses felt pressurized and hot (the cold side just a little bit cooler) after parking it. So I drove it around today with my INPA laptop so I could make sure first of all that the temperature gauge on the cluster was reading the correct value of the coolant outlet temp. I also wanted to monitor the inlet vs outlet temperatures to ensure it was cooling adequately

With the coolant temp pulled up on the "secret" menu (shown above with the car off) I was able to confirm that the coolant temp gauge is showing the engine outlet temp which is correct. I drove it about 10 minutes after it hit operating temperature. Most of the time it was completely fine... the inlet would go up to ~97 after driving hard then down to ~93 or so when idling or driving slow. The outlet temp was mostly around 100 but never exceeded 105 which is the proper operating range for an N62 as they have 105C thermostats and will vary their operating temperature from about 99-105C in my other cars


The secret menu test also shows RPM and I was able to verify that the RPM is reading correctly. That wasn't a major concern for me but it was good to double check that and confirm it is displaying the right values


It did get a little hot on the radiator outlet side so a few days later I worked on getting some ducting in place and went on a quick test drive to test it, worked well, kept things a few degrees cooler even though it was hotter, so now I will fashion something I can bolt into place. Took a few pics while it was out

Since getting the dual intake back on hasn't been a major priority, I decided to paint this radiator core support because I got really sick of seeing that silver standing out like a sore thumb. I really dig how everything being black seem to really nicely accent the engine

The weather broke for a single day over the summer and was quite a bit cooler. I spent an hour or so in the morning modifying and retrofitting a radiator duct piece and got that installed and took it on a long drive

Pulled over to take some pictures during the drive - and also to let it idle for a bit and see what the temps were

Temps were much, much better, although on the highway, the radiator outlet temp was getting very close to the engine outlet temp

I then discovered something I should have caught much earlier, the fan behind the radiator was actually pushing instead of pulling. So it was blowing forward and when the car was moving the fan was blowing against the air that should be flowing through the radiator. And at idle the front aux fan was pushing through the radiator and the fan behind the radiator was pushing forward. This resulted in very little airflow through the radiator and when moving it would actually have less airflow than when at idle


What I ended up doing was retrofitting a lower profile fan, so that I would be able to reinstall the dual intake in the near future. However after getting the electric puller fan retrofitted to the Z3 fan shroud I plugged it in and tested it and it didn't work. D'oh. So what I ended up doing was removing the fan blade from the puller fan to install onto the fan motor that I knew worked. The fan blade angle is what determines the direction of air movement so by swapping the fan blades from the puller fan onto the working motor the direction was correct

I took it on a very long test drive after fixing the fan issue and coolant temps stayed perfectly in line, the radiator outlet temp was a bit hotter than my N62 X5 but I expected that to be the case. The engine outlet temp dropped from 105 (which is still ok for this engine) to 99 for most of the drive, which is great. Outlet was mostly in the low 80's and while driving would drop to 63. Below was at the end of that long drive after letting it idle

I then sourced some seats - actually traded a little labor and diagnostics for them so no out of pocket cost. It will be nice to get a passenger seat in there so I can take my fiance for a drive!

They aren't in amazing condition - the driver's seat is actually pretty nice but a little dusty. I think it was reupholstered at some point. The passenger seat is clearly original leather and has a few splits at the seams... I'm gonna use them for now, but will probably get them reupholstered in the near future. They are also from a facelift Z3 so I need to swap the seat bases to my older style seats


But before doing that I wanted to address a more pressing matter - the high IAT's (intake air temperatures). The air filter up until now was shoved in the engine bay, behind the headlight, it was a low pressure zone as when moving air is sucked out of the engine bay so less air was available but perhaps more importantly is the fact that the air that was available was hot air that had passed through the radiator. I was seeing IAT's up to 50% higher than ambient temps and I could feel the car losing a bit of power once everything was up to temp


So I removed the radiator core support and installed the one I modified for the dual intake and ordered the parts needed to finish that up

I've also made a few other modifications with this change. Because the A/C doesn't work I will not be reinstalling the A/C condenser. This should allow a cleaner more direct route for air to pass through the radiator. But the front stock aux fan mounts to the condenser so what I have decided to do was install an aftermarket electric fan I had which will be mounted directly to the radiator and wired into the stock aux fan wiring


Once I got the 90 degree elbows I was able to mock things up a bit better and it's looking great!

Below is the view from the brake duct opening looking up, clearance is a little tight with the headlight in but should just barely fit the 3" pipe I have coming

I'm going to repurpose the 45 degree elbows I originally had up top to (attempt to) angle the filters forward slightly into the airflow

Got the fan wired in...

Then I tested it and high speed worked but low speed wasn't working. Went through all the troubleshooting steps... relay was clicking, relays worked when swapped from low to high speed, no blown fuses, had 12v at the plug... so I snipped the wire after the resistor, checked for any voltage past the resistor and there was none. Cut the wire before the resistor and bypassed it. Worked perfectly


Soo... ended up replacing the resistor and cleaning up the wiring a bit in the process as well. Now the low speed works perfectly

Then the intake stuff arrived so I got that installed as well

I got it out for the first time today with the dual intake installed and was very impressed. IAT's were dropped fairly significantly - from over 65C to just over 50C at idle and lower when moving, keeping in mind its 110 (43C) here right now that's not too bad imo. It also picked up a noticeable amount of power and more importantly, it didn't seem to lose power the longer I drove it lol. Coolant temps were also rock solid - after a really long pull the highest I saw was 102 at the engine (up to 105 is ok for this engine) and 85 at the coolant outlet so I think removing the condenser helped get better airflow straight to the radiator and the aftermarket aux fan seems to be doing it's job

I also spent a little bit of time cleaning it and getting all the other random engine bay stuff installed over the past few days so here are a few shots of the engine bay in pretty much it's final form... the only thing left to change mechanically will be to add the power steering. And when I add the fender liners those will be visible from under the hood but other than that, here it is...

Looks good in the engine bay, in the next post I focus (a little bit) on exterior cosmetics!

0 comments