Well... shit. Over the course of a day of daily-driving back in Feb (all in-town, dropping my son off at school, going home, running an errand etc) Vera started misfiring sporadically, then almost constantly above 50% throttle, until the low oil buzzer went off as I was getting home and I pulled the intake off and found that it was completely oil soaked. I check the oil level regularly, and had changed it about 600 miles before (that mileage spanned 6 months and two HPDE days, plus the first ice racing event), so I know it didn't start off low. The catch can that I had installed when chasing down a similar issue at a track day a couple years ago was completely full too (the catch-can has been dry almost since I installed it, the issue was topping off the oil in haste before my session with the engine idling - some got sucked into the various vacuum lines). Anyway, even a small amount of time running would result in pumping a lot of oil out of the crank case and into the catch can, then into the intake. The engine started up pretty well (as long as the MAF and plugs were cleaned of the oil), and idled fine, but rotor 1 was low on compression on all faces. Anyway, after taking apart and cleaning the intake, oil fill manifold, and the associated tubes a couple times, I had convinced myself it was rebuild time.
So, on to the rebuild, the rear rotor looks pretty much fine... a bit of wear evident on the housing plus 2 minor gouges (not sure what those were from), and one of the side seal springs had broken apart into a few pieces, but all the pieces were still contained behind the side seal. The front housing was a bit more roughed up, and two of the three side seals on the center iron face of the rotor were at least half-missing, with no springs left behind them and only a couple tiny bits of metal found on the trailing plug face and in the exhaust port. The oil seals on all rotor faces were intact and appeared undamaged.
So now, repair plans:
First, I'm planning on new housings front & rear - the front has some obvious damage from bits of the side seals getting driven into the exhaust-face of the housing, so I don't think this one would be reusable even if it could be re-surfaced.
Otherwise there are minor scratches, most of which I can't quite catch a fingernail on. There's also a bit of a different wear pattern in the center vs sides along the housing, with some slight chatter marks, but none of this seems unreasonable for an engine with 93k miles on it. Oddly, there are some notable grooves running around the whole inner circumference of both the front and rear housing that don't seem to be mirrored in the apex seals, and the rear housing also has some similar evidence of something getting driven into it by the rotor on the exhaust portion of the surface. Maybe bits of the front rotor side seals made their way into the intake and over to the rear rotor? Either that or this engine has been apart before and the housings were re-used. There was a lot of RTV squeeze-out between the housings, irons, and sump, and the clutch is pretty new, so maybe?
On to the irons - the wear pattern looks pretty normal I think, with the exception of a couple spots. The trailing edge of some of the ports looks a little chewed up by bits of broken seal that got caught there, the finish on the trailing edge of the exhaust port does not seem as smooth as elsewhere, and particularly on the front face of the middle iron, there are some deeper gouges and divots presumably from the side seals coming apart (this was the face that the broken seals were riding on).
Front iron, mostly good except for some chewing on the trialing edge of the lower intake ports and different finish on trailing edge of exhaust port:
Middle iron, front face, definitely some damage at the trailing edge of the intake port and on the sliding surface from breaking seals:
Finally, the rotors. The rear rotor looked fine - some carbon deposits but thats not unexpected. The front rotor was a bit more scuffed up, including scrapes around the rear face presumably from the side seals coming apart.
Also, on the leading edge of the apex seal groove there was a bit of metal junk building up. Its definitely sticking proud of the machined surface, and doesn't seem like its been pushed up from inside the apex seal groove (not sure how this would happen, especially on the leading edge of the groove and not on the trailing edge), so I'm guessing that this is what happened to the missing parts of the seals and their springs... most of them got chewed up and squashed by the rotor here, getting stuck as the rotor spun and dragged them along until they hit the apex seals. This is on all 3 apexes of the front rotor, only on their leading edge, and is not apparent at all on the rear rotor.
The apex seals mostly look good, and I'm on the fence about re-using them, but figure if I'm getting new housings, may as well get new apex seals to try to get as much life as possible out of the rebuild.
So, anyway the plan is to try to get good-condition used front and middle irons (Thanks Kevin!), or barring that get the ones I have re-nitrided. Clean up the rotor surfaces and that debris on the front rotor apex groove, get new housings, apex seals & springs, side seals & springs, corner seal springs, and all the soft seals (all the oil seals and bearings look like they're in good shape). The corner seals themselves all look good, but I still need to look through the FSM to see if there is a spec to measure them to.
