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


Short video of ripping it around... just shy of full throttle (still don't have a pedal stop installed)

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


However, the engine outlet temp was completely stable and maintained its temperature perfectly. I am starting to suspect that part of my issue is the location of the radiator outlet temp sensor. I have it installed directly on the thermostat

So I think what may be happening is when the engine is at full operating temperature and the thermostat is closing/opening (as the electronically controlled thermostats are designed to do) to maintain a certain temperature, some of the engine outlet coolant makes its way down to the radiator outlet temp sensor. I think I need to relocate the sensor to closer to the radiator to ensure the measured value is in fact the radiator outlet temp, without mixing with the engine outlet


If it does end up that the radiator outlet temp is too hot then I may end up sourcing an even larger capacity radiator in an attempt to get temps under control but I am not even positive at this time that it is an issue given the incorrect outlet temp sensor location and because the more critical value, engine outlet temp, has been staying perfectly stable. There is a radiator on the market with a 55mm depth, the one I have now is 38mm. The company that makes the 55mm makes their own radiators in house and they also offer 68mm cores, so I think if I decide to go with a larger radiator, I may see if they can make me one with the 68mm core. Obviously surface area is more important than depth, but lacking the space for more surface area - but with plenty of room for more depth - I think the 68mm would be the way to go. That would also mean more coolant volume which would also be helpful but of course the most important factor is being able to sufficiently cool the coolant I do have in the system


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