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From: James Brewer <alpha@concordnc.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Date: Sat, 20 Aug 2005 11:09:04 -0400
Message-ID: <20058201194.268295@alphasys>
In-Reply-To: <list-675491@logan.com>
Subject: Re: [FlyRotary] Re: Rotary Diagnosis please
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Ed,
Thanks for the insight into these seemingly simple little metal=
 "bracelets".
I measured the bright shiny lip as best as I could but I think someone=
 mentioned
that being .020 inch.  Hard to be sure you're measuring edge to edge with=
 old eyes.
I will replace the rings to be on the safe side.  Factory manual talks about=
 the springs
for these having cream and blue paint but mine didn't have any.  They looked=
 the same
and I thought I got them in the correct position...but....

Jim


On Fri, 19 Aug 2005 23:21:22 -0400, Ed Anderson wrote:
>=A0Jim,
>
>
>=A0The metal rings that retain the oil "O" rings have a very small
>=A0range (in my opinion) operational spec. =A0I have measured them even
>=A0after 100 hours and found them to be just within the spec. =A0I
>=A0suspect that they wear quickly when seating in new side housings
>=A0and then the wear factor drops way down. But, I have never taken
>=A0apart an used engine and found the metal rings reusable (based on
>=A0the Mazda spec for wear). =A0Not to say they would not work - but
>=A0they were not within the Mazda specs for wear.
>
>=A0They have a rather sharp =A0metal ridge (actually the edge of the
>=A0metal ring) that rides against the side housing (and scraps off and
>=A0seals the oil in the center housing from the combustion chamber).
>=A0This ridge/edge =A0will show a bright wear mark. =A0The width of this
>=A0worn spot on the outer surface of the ring determines (according to
>=A0the Mazda manual) whether the Metal "O" ring holders are within
>=A0specs. =A0Apparently when this ridge wears flat enough then there is
>=A0sufficient flat surface area for the rings to hydroplane on the oil
>=A0rather than scraping it off the wall (just a WAG on my part).
>
>=A0But, if you are burning oil, then my bet is the metal "O" ring
>=A0holders.
>
>
>=A0Ed A