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12-11-2009, 07:07 AM
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Join Date: Aug 2009
Location: Ottawa, Canada
Posts: 108
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So, About those pre-oilers?
Hi. Interesting thread, since not much is written about pre-oilers for flat engines. I fly some warbirds, and pre-oiling is mandatory in our organization for the old engines. I was assuming it would help in a Lyc too.
Anyone care to take a stab at a few specific questions?...
What proportion of RV's use pre-oilers? Do the engine shops recommend them? Is it worth the additional weight forward of the firewall? What systems are on the market?
Thanks in advance,
Rob
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12-11-2009, 07:59 AM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Quote:
Originally Posted by pierre smith
Hey guys,
Just fly more and the lobes will stay wet!
Seriously though, my late boss had a P-51 which ate cam lobes since they ran directly on top of the rocker arms. After he started adding 10% STP, the lobes lasted and lasted and...since it doesn't evaporate/drip off like 20W50.
Mahlon, is 1 pint of STP OK in a 4 banger Lyc?
Regards,
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I don't know about STP but I am a believer in AVBLEND. It supposedly will keep the top end oiled between engine runs.
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Last edited by David-aviator : 12-11-2009 at 08:02 AM.
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12-11-2009, 10:57 AM
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Join Date: Jun 2007
Location: Rhode Island
Posts: 937
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Quote:
Originally Posted by Rob Erdos
What proportion of RV's use pre-oilers? Do the engine shops recommend them? Is it worth the additional weight forward of the firewall? What systems are on the market?
Rob
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Hi Rob, I would guess that less than 1% of RVers use pre-oilers. There was a guy named Joachim Beh on the Lycoming List who made his own, beautifully constructed pre-oiler which consisted of a panel-mounted plunger similar to a priming plunger with two check valves. Not sure if he is on this forum or not, but if you search the Lycoming list's Yahoo group archives you will find some really nice photos.
I always wondered why there wasn't a system which was essentially "ground support equipment" - used only on those occasions where you haven't flown in over a month or whatever - you pull one of the two oil gallery (galley? I always get confused) plugs at the front of the engine and install your pre-oil hose, turn on the flow from your pre-oil tank which is pressurized with shop air and has a diptube to draw oil from the bottom of the tank (old propane tanks work great for this if modified to add a diptube, ask me how I know  ). Once you've pumped in a quart or so, disconnect the hose and reinstall the plug, torque, and go fly.
This approach eliminates airborne weight, complexity, and leak points. You do need to make sure you torque the plug (safety wiring it would be a great idea too)
I had Mattituck add the cam squirts to my case so pre-oiling thoroughly wets the cam lobes and followers. They make a very fine atomized mist which soaks everything starting at the top of the case. Obviously, all of the journals are lubed as well.
With pre-oiling and a DIY dehydrator to remove water in the oil generated from combusting fuel, I would think your Lycosaurus would last a long long time, unlike the engine I just finished overhauling, which had badly spalled cam followers and a shot camshaft 
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Highest Regards,
Noah F, RV-7A
All men dream, but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men? for they may act their dream with open eyes, to make it possible. -T.E. Lawrence
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12-12-2009, 09:30 AM
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Join Date: Aug 2009
Location: Littleton, Colorado
Posts: 182
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Quote:
Originally Posted by airguy
Does anyone here use the engine pre-oiler devices to supply oil pressure to a cold engine just before start? I've seen two basic types, an electric pump and an accumulator style. Do they work well enough to be worth the weight and complexity? How would you even know without running to TBO and tearing down?
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Yep, I run a 3 qt accu-sump (accumulator, air pres./ oil) system with an electric solenoid to activate. Feeds directly in to a modified oil screen housing. Works great, serves me 3 purposes, 1) pre oilier. 2) Provides oil pressure to engine during sever aerobatics. 3) Keeps 3 qts out of the motor from getting aerated when flying inverted. Defiantly the way to go, especially if you plan on doing 0 g?s and or negative hanging.
Thomas Shpakow
www.g3inition.com
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12-12-2009, 10:38 AM
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Join Date: Jul 2006
Location: Corvallis Oregon
Posts: 3,547
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Same here
I use a 1.5 qt plunger style (Morrosso) for the same reasons as listed above..seemless oil pressure when going from positive to negatibve G and back
Frank
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12-12-2009, 11:47 AM
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Join Date: Mar 2005
Posts: 22
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Questions for those with Oil/Air Accumulators
For those of you using oil/air accumulators, I am curious about how much time is available (at zero or negative Gs) before the oil pressure drops off. Also, please advise if your aircraft has an oil-controlled Constant-Speed prop?
Thanks
Blake Harral
RV-4 N72RV
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12-12-2009, 05:19 PM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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Quote:
Originally Posted by pierre smith
Hey guys,
Seriously though, my late boss had a P-51 which ate cam lobes since they ran directly on top of the rocker arms. After he started adding 10% STP, the lobes lasted and lasted and...since it doesn't evaporate/drip off like 20W50.
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Merlins that haven't been overhauled in the last few years tend to eat cams because the chrome plating wears off the followers. There's a guy in Canada that has an STC for followers that have a carbide tip brazed to them, they're called "merlin fingers" and they completely eliminate the problem. The guys at Roush hand delivered a camshaft to a Reno racer this year that discovered a cam lobe that had completely worn down to round...and the thing still ran in that condition.
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Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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12-12-2009, 05:33 PM
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Join Date: Aug 2009
Location: Littleton, Colorado
Posts: 182
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QUOTE=bharral;385682]For those of you using oil/air accumulators, I am curious about how much time is available (at zero or negative Gs) before the oil pressure drops off. Also, please advise if your aircraft has an oil-controlled Constant-Speed prop?
Hello Blake,
With engine oil temp @ 180f the there is about 15 ? 20 seconds bleed down when the engine is not running and I switch the system on. In the air after flipping over to invert waiting for the Christian 801 system to prime I see a drop in oil press to a minimum of 50 ? 55 psi, were as in my Citabria flipping to invert, it went to zero psi for that brief (3 ? 5 sec.) moment, Citabria had the same system 801 C. Knife edging is extended 20 ? 25 seconds depending what side you knife edge on (lower oil pick-up tube high side) before there is fluctuations. The prop is oil controlled, do not see any rpm fluctuations. When pre-oiling cold, discharge @ 65 - 70 psi, temp @ 50f, 2 minutes. My system holds 3 qts.
Thomas Shpakow
www.g3ignition.com

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12-12-2009, 05:40 PM
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Join Date: Jul 2008
Location: Camas, WA
Posts: 481
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Wondering
Would pulling the prop through 6 or 8 blades before starting do the same thing? (pre-oil everything)
Or how about letting that many blades go by before introducing fuel on the first start of the day?
DM
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12-13-2009, 04:15 AM
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Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 1,628
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For those of you useing oil accumulators, where do you plumb into the engine? I am about to install a one quart Accusump.
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Ron Schreck
IAC National Judge
RV-8, "Miss Izzy", 2250 Hours - Sold
VAF 2021 Donor
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