I'm having rear main seal/oil leak issues that I can't figure out. My car is an 85 SpecRx-7 racecar with a reman 12A (emissions equip. removed). I don't know the history of the engine as I bought it used. The rear main seal failed during the car's shakedown run at an autocross a couple of weeks ago. When I changed the seal last week I found that it was partially torn and pushed out against the flywheel. I assumed that it was just a bad installation, so I replaced the seal as well as the stationary gear o-ring while I was in there. I made sure the outer seal surface was completely dry and the inner lip seal was lubricated during installation.
I took the car out last Friday for a lapping day at my local roadcourse Friday and experienced oil leaks around the seal again and was getting lots of oil in the vented catch can I have attached to the filler neck vent. The other vent fitting on the intermediate housing is capped. I pulled the flywheel inspection plate today and noticed the replacement rear main seal had pushed out against the flywheel again.
The engine does not smoke, but seems to be down on power. I checked for blowby by running the engine in neutral at high rpm's, but I don't see any signs of pressure coming out the oil fill vent. The possible causes that I can come up with are: the oil return passage from the rear seal housing to the pan is plugged, the oil passage thru the eccentric shaft from the rear main bearing is restricted, or the bearing clearance is out of spec allowing oil to blow into the seal housing. I'm new to rotaries. Are any of these scenarios likely or common?
Thanks,
Troy

 

I read this in the other section you posted in and still don't have a good answer for you. If it was caused by oil pressure, it would show else where, even on the oil pressure gauge. That leaves me with one possible guess, and it is only a guess. There may be too much end play in the e-shaft. But that would cause other issues that would show up, eventually anyway.

You might post your question in the engine building section, or over at nopistons.com in engine building and portingsection. There's a good group of proffesional builders that frequent over there.

 

Everything is pointing to too much crankcase pressure. I've never experienced this with a rotary though. On Volvos which have the same style rear main seal if the flame trap for the crankcase ventilation gets clogged it will blow the rear main seal out completley.

 

Thanks for the replies. Not a good sign when 2 of the most experienced people on this forum can't quite figure it out....

 

It's an odd one that I've never run across it before. What does your oil pressure run? If it's in the normal range, I have no idea.

 

Oil pressure seems to be normal. I must be getting some blowby that only occurs under load when I can't observe it directly. I posted on "nopistons" tonite to see if anyone there has any ideas.
Thanks again,
Troy

 

The only real bad blowby problem that I have come across is with a Sa engine that had sat for many years since a rebuild. I was able to get it running but nothing I did would bring the compression back up. Under hard RPM's it would literally blow the dipstick out of the tube and start a geyer of oil. I found some seal problems pertaining to the low compression and I believe an oiling problem with the rear bearing. But I never really pursued it because I just put another motor in it.