Jim Mosur wrote:
Hi Paul.
I guess misery likes company.
Last Friday on climb out at about 300 ft. I felt a slight bang, RPM dropped about 400, thought I had lost a plug or injector,
engine continued to run smooth just down on power, I continued around the circuit and landed. When I tried to idle the engine
after landing it was extemely rough , anyway the following day I went thru checks on injectors , plugs, timing etc. then
compression check, 2 rotor ok ,1 rotor nada. Disassembled engine following day. I found the 1 rotor had shed a end seal which
took part of the apex seal with it, gouged quite badly the rotor and chamber face although not as bad as Chucks, inter. and end
sections ok. I hope to have this thing back in the air in a week or so.
I had experienced a large increase in oil consumption starting about 25 hours ago, I checked the oil seals on the rotors and
they seemed ok, but I guess the search will go on to see if there is a connection.
Jim Mosur
RV 6
Brampton Ont.
While you have it down Jim put those TES O-rings in the oil scraper rings.
Also check and see if the scraper rings are still in spec.
That is the usually the reason for high oil consumption. Have you been mixing
2 cycle oil with the fuel or are you using the oil injector pump?
If you have been using the oil injectors pump several failure modes
are possible. I have seen instances where the oil fails to distribute
over the insides of the rotor housings. Hence the corner seal may
not have received its fair share of lube oil. This does not happen
when 2 cycle oil is mixed with the gas. Believe it or not the main
function of apex seal oil is to cool the apex seals.
If it is ported and it was done just slightly wrong you can
lose support for the corner seal as it passes over the intake port. Check
with Dave Lemon or John at Mazdatrix. They have had their problems with
corner seals. The corner seals also have a tiny rubber insert to damp
a vibration mode I suspect. If the rubber goes away from long term
heat the very hard seal can shatter when you hit that resonant frequency.
The RX8 engine has two changes in this area. There are now two injectors per
rotor mounted such that they are aimed at the corner seals. The corner seal itself
is much smaller allowing larger intake ports.
Paul Lamar
BTW while we are on this subject there are two main kinds of 2 cycle oil.
Here is a chart showing the differences. Looks like the stuff for water
cooled engines is better for our purposes.
Paul Lamar
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