Mailing List flyrotary@lancaironline.net Message #26018
From: James Brewer <alpha@concordnc.com>
Subject: Re: [FlyRotary] Re: Rotary Diagnosis please
Date: Sat, 20 Aug 2005 11:09:04 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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:
 Jim,


 The metal rings that retain the oil "O" rings have a very small
 range (in my opinion) operational spec.  I have measured them even
 after 100 hours and found them to be just within the spec.  I
 suspect that they wear quickly when seating in new side housings
 and then the wear factor drops way down. But, I have never taken
 apart an used engine and found the metal rings reusable (based on
 the Mazda spec for wear).  Not to say they would not work - but
 they were not within the Mazda specs for wear.

 They have a rather sharp  metal ridge (actually the edge of the
 metal ring) that rides against the side housing (and scraps off and
 seals the oil in the center housing from the combustion chamber).
 This ridge/edge  will show a bright wear mark.  The width of this
 worn spot on the outer surface of the ring determines (according to
 the Mazda manual) whether the Metal "O" ring holders are within
 specs.  Apparently when this ridge wears flat enough then there is
 sufficient flat surface area for the rings to hydroplane on the oil
 rather than scraping it off the wall (just a WAG on my part).

 But, if you are burning oil, then my bet is the metal "O" ring
 holders.


 Ed A

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