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07-22-2014, 06:50 AM
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Super Moderator
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Join Date: May 2005
Location: Locust Grove, GA
Posts: 2,627
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Two types
I have used both Aeroshell 100W+ and Philips 20W50, both with cam guard. Just a data point.
Vic
__________________
 Vic Syracuse
Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
Kitplanes "Unairworthy" monthly feature
EAA Sport Aviation "Checkpoints" column
EAA Homebuilt Council Chair/member EAA BOD
Author "Pre-Buy Guide for Amateur-Built Aircraft"
www.Baselegaviation.com
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07-22-2014, 02:21 PM
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Join Date: Sep 2009
Location: St. Louis, MO
Posts: 1,788
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I have decided to abandon the exhaust port system. After just 8 hours I can start to see a build up again, this after reducing the exposed area of the spigot in the exhaust pipe. I am leaving the AO sep installed and dumping the vent overboard next to the exhaust pipe.
Until a proven solution is discovered, this is just too risky for me, even with a safety check valve.
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Bill Peyton
RV-10 - 1125 hrs
N37CP
First Flight Oct 2012
Aviation Partners, LLC
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07-25-2014, 11:24 PM
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Join Date: Nov 2010
Location: West Linn, Oregon
Posts: 1,351
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I was thinking about this today when I came across a copy of an old Cessna AD - 82-07-02 that addressed ice blockage of the breather tube. The solution prescribed was to cut an alternate air outlet in the tube as a precaution. A simple solution to prevent a head gasket from blowing.
In our case, it's the coaking/tar issue, but if the valve was to become blocked, at there there would be an alternate air vent. Same principle as the second check valve, but cheaper/easier.
The hole that is cut isnt that large, so there would be some back pressure, but better than blowing the engine.
http://rgl.faa.gov/Regulatory_and_Gu...E?OpenDocument
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CharlieWaffles - But you can call me " Mark"
RV-10
N928MT
Flying - AKA Still Tinkering
Build Project Site
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07-25-2014, 11:42 PM
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Join Date: Jan 2005
Posts: 3,646
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Yes, would an ASA setup with a whistle slot/hole in the breather line address the potential negative side effect of the stock ASA installation?
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Steve M.
Ellensburg WA
RV-9 Flying, 0-320, Catto
Donation reminder: Jan. 2021
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07-26-2014, 04:09 AM
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Join Date: Dec 2008
Location: Ontario, Canada
Posts: 464
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Whistle slot
I had cut a whistle slot in the rubber tube going to the reed valve. It did not work.
Gary
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07-26-2014, 08:04 AM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Remember that part of the benefit of the check valve- to-exhaust configuration is the negative pressure delivered to the crankcase. Cutting a hole in the tube eliminates that possibility.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
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Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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07-26-2014, 08:09 AM
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Join Date: Oct 2005
Posts: 1,516
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You cannot open even a small whistle slot and retain the negative pressure resulting from the installation of a Reed valve. The only way to keep the system working as it was intended without the risk of coking up the breather stub is to install a second reed valve.
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Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 600 plus hours
Running on E10 mogas
Don't believe everything you know.
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07-29-2014, 07:25 AM
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Join Date: May 2006
Location: Houston
Posts: 2,012
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Here's a pirep for the ASA oil separator. IO-360 blowing 1 qt every 3-4 hrs out the vent. Installed the ASA system (without the tailpipe connection). Flew to Oshkosh (after 1-2 hr lcl test), and it works just as advertised.
As for connection to the tailpipe, my time working in petrochem mfg tell me the coking issue is not going to be solved without elaborate cooling, purge or a flush stream. FWIW, that makes this option too complex/unreliable for me personally. You want negative crankcase pressure, route the effluent through a vacuum pump!
Bryan
Houston
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08-03-2014, 03:38 PM
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Join Date: Apr 2005
Location: Indepenence, Oregon
Posts: 342
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Temperaturee data for RV-10 coking issue

Ok, here is a major correction of my post #177 in this thread. (Edited with a correction)
I strapped my engine compartment thermocouple to the outside of the pipe right about where the coke formed. When I took the cowl off to put in the relief valve, the thermocouple was not on the pipe. I used a tie wrap to hold it on and it was melted! Suspect it was reading local air temps near the exhaust pipe after reaching its high temp.
Installed thermocouple with a clamp. Flew up to a wedding yesterday and temps were much higher the entire flight. The above graph is the temperature on the outside of the pipe at the weld to its mounting plate.
The temperature on the inside of the pipe that the oil mist sees is most likely somewhat higher. This is obviously conductive heat from the pipe and perhaps some heating from the exhaust impingement on the small piece that is in the exhaust flow. The drop in temperature near the end was during a descent from 8.5K to 4.5K at full throttle, engine leaned to peak plus .5 GPH.
I would like Alan to get some data on the temperature of his inner pipe for the pipe in a pipe solution. The inner pipe will be subjected to much less conductive heating, but still will see the exhaust gas.
I do love the clean belly and the lack of small leaks that all Lycs seem to have. But despite the addition of a relief valve, the coking issue has me looking a eliminating the vacuum idea and just exhausting it onto the exhaust pipe.
When I added the relief valve after just about 1.0 hours from completely cleaning the coke off the inside of the pipe, there was a very small buildup starting.
__________________
Bruce Patton
Rans S-20 Raven 796S flying since 2019 (slowly)
RV-6A 596S flying since '99 (Sold)
HP-18 5596S flying since '89
RV-10 996S flying since 2014, quick build wing and slow build fues., - dual Skyviews with complete system, two radio and not much else. Interior completely finished with Zolatone. CF plenum. 1624 lbs, FLYING after a 21.5 month build.
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08-04-2014, 11:51 AM
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Join Date: Nov 2005
Location: San Francisco, CA
Posts: 525
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Thus we have this graph from BillL's post with Bruce's graph. The coking curves start at 200C or approx 400F. Hitting 400F+ inside the tube seems highly plausible to me.
http://www.vansairforce.com/communit...&postcount=141

__________________
#40533 RV-10 Builder and CFI
1/2006 Started build
10/19/2011 First flight
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