Troy85RX7

I posted this on the RX-7Club.com, but no one could give me an answer and they sugegested that I post here.



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 monday 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

Lynn E. Hanover

Your test was the right idea, but it needs to be done under load at full throttle. On the other hand the results will be the same. The seal will pop out and or, the catch can will fill up.



You have a very tired engine. It probably has some broken corner and or side seals. So the engine is breathing more than it should. It just means that combustion gasses are blowing past the seals and into the sump.



Clean up the seal again and glue it into the gear with nonhardening permatex. If you like to screw with things, make up two "S" shaped metal straps that bolt on with the rear gear bolts and reach around the edge of the seal to hold it in place.



If the rules allow increase the breather tube size to 3/4". If not use any opening into the sump as a breather.



If the rules say breathers are free, check the drawing. If not I used to put one right through the filler cap.



The larger the total breathing cross section the lower the gas velocity. The lower the velocity the lower the amount of oil it can carry away to the catch can. Use large diameter hose and run it uphill to the can.



If you are allowed to run a baffle plate, make one with just a 3" diameter hole under the center iron. And a small one to fit tight around the oil pickup. That will help oil control in the turns. I can picture that for you if you need it.



Lynn E. Hanover

Troy85RX7

I'm already running the Mazdaspeed baffle plate and have a Jaz 1 quart catch can w/ a 2" dia. vent w/ filter. Only has a single 1/4 " inlet though. I'm going to tear the engine down and rebuild rather than try the band-aid approach to keep it going.

Thank you,

Troy Marcella