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Date: Mon, 24 Oct 2011 20:07:01 -0400
From: Ernest Christley <echristley@nc.rr.com>
Reply-To: echristley@att.net
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: oil in the gearbox
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I finally got my flywheel/generator/blower back from the machinist 
Friday, and stayed up late putting everything back together.  I was 
anxious to test the engine with a balance flywheel, injectors oriented 
to blow down the intake runners the correct way, and a new rear section 
to my gearbox that replaced the back-end made up of three individual 
plates (I turned a single piece that holds a plate bearing, a large 
roller bearing, a shaft seal and provides for mounting the generator's 
stator.

Late Saturday morning, I had it all back together, battery charged, and 
gas in the tank.  Rolled the fuselage into the driveway and cranked on 
the starter.  Sound of the starter chewing on the tips of the ring gear 
teeth.  Get out.  Tighten the starter up a bit.  Clear prop!! and some 
nice smooth turns.  It was trying, but couldn't quite get started in 
about three attempts.  On the fourth try, it caught and belatedly came 
to life.  Tickled the throttle a bit, and it sprang to action, the 
125Hp@6000rpm load prop spinning a healthy 3000rpm.

The EGT for the rear iron wasn't waking up.  I got out and fiddled with 
the plugs.  They didn't seem to be flooded, though the top was a little 
wet.  Cleaned the plugs off with a butane lighter, put the back in and 
it started right back up, burning rich with the AFR bouncing between 12 
and 13.  Oil pressure was strong, and the throttle adjustment met with a 
smooth adjustment in rpm, even if the engine wasn't running quite as 
smooth as I remember.

As I was watching the water temps come up to the operating range, I 
heard the "poof!" and saw the cloud blow out the front of the engine.  I 
was sure I blew a water line (probably because I had water on the brain 
right then), but when I got out after quickly shutting down there was a 
quart of oil under the gearbox on the driveway, and the front seal had 
blown off.  Adding to the frustration of dashed hopes of a smooth 
running engine, the forward half of the half-primed fuselage was covered 
with a spray of motor oil.  I'll have to wash it down with some serious 
de-greaser before I can finish priming.

A tear-down revealed that I failed to cut the exit oil galley that was 
integral to the original rear section of the gearbox.  I was pumping oil 
in at 90psi, and it had now way to get out.  Well, that is, until it 
made a way.  8*)   Three minutes at the milling machine that's dressed 
up to look like a drill-press, and the oil now has lost of room to get out.

The question I have is do I need to replace the front and rear oil 
seals.  I pressed the front oil seal back in, and even added a couple of 
retainers, as Lynn has suggested;  but, should I replace it with new 
one, even if it doesn't leak?  I put a rubber hose over the oil inlet, 
and blew into it.  I could hear it bubble out of the rear seal when I 
covered the oil outlet.  How much pressure should those rubber seals be 
expected to contain?