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  #11  
Old 08-02-2021, 11:02 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
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the pic shows a VERY clean breather tube, even the inside of the tube. It is typically coated with an oily film. Any signs that oil is coming out of it? If not, the breather line could be blocked and that would force oil out of the crank seal. If the breather is blocked, excess pressure builds in the crankcase and the easiest way out then is the main seal.

YOu have an engine issue, not a 10 issue.

Larry
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Last edited by lr172 : 08-02-2021 at 11:05 AM.
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  #12  
Old 08-02-2021, 11:40 AM
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Cbull Cbull is offline
 
Join Date: Feb 2013
Location: austin, TX
Posts: 74
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Quote:
Originally Posted by lr172 View Post
the pic shows a VERY clean breather tube, even the inside of the tube. It is typically coated with an oily film. Any signs that oil is coming out of it? If not, the breather line could be blocked and that would force oil out of the crank seal. If the breather is blocked, excess pressure builds in the crankcase and the easiest way out then is the main seal.

YOu have an engine issue, not a 10 issue.

Larry
There is definitely oil coming out of the breather tube. That's actually the only place I see oil after I run up the engine. The discharge location of the tube seems questionable to me. It faces forward, well above the bottom of the fuselage, perhaps 2" or so. If there is turbulence there, it might be spreading everywhere. Maybe the crank seal is leaking in flight, but not while on the ground and running full static rpm.
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  #13  
Old 08-02-2021, 04:26 PM
BruceW BruceW is offline
 
Join Date: Aug 2005
Location: Elk Grove, CA
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How bout this . . . .
Forward facing crank case vent tube is somehow getting pressurized with the cooling exit air and creating increased crank pressure, enough now to go thru the forward crank seal.

Way to test; clamp flex tubing to end of vent tube with a turn BACK with the exit air. Leave it plenty long out the exit space. Then cowl back up to get the exit air direction and go flying. No oil, Im right. Oil continues, never mind. https://vansairforce.net/community/i...es/biggrin.gif

Just some mid-day armchair engineering.
Good luck.
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  #14  
Old 08-02-2021, 04:47 PM
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Cbull Cbull is offline
 
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Location: austin, TX
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Quote:
Originally Posted by BruceW View Post
How bout this . . . .
Forward facing crank case vent tube is somehow getting pressurized with the cooling exit air and creating increased crank pressure, enough now to go thru the forward crank seal.

Way to test; clamp flex tubing to end of vent tube with a turn BACK with the exit air. Leave it plenty long out the exit space. Then cowl back up to get the exit air direction and go flying. No oil, Im right. Oil continues, never mind. https://vansairforce.net/community/i...es/biggrin.gif

Just some mid-day armchair engineering.
Good luck.
That is exactly what I'm thinking. This afternoon I bought a 4" length of heater hose with a 90 in it. Clamped that on, it is now below the surface of the fuselage pointing straight down (still inside the lower cowl) I did a flight around the pattern and no oil. Checked the crank seal and it's dry. As soon as some storms pass I'm going up for a 30 min flight to see how it does.
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  #15  
Old 08-02-2021, 05:37 PM
wilddog wilddog is online now
 
Join Date: Feb 2008
Location: va.
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Oil will slowly eat up heater hose. Use hose rated for oil.
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  #16  
Old 08-03-2021, 03:49 AM
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cderk cderk is offline
 
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Location: Park Ridge, NJ
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Quote:
Originally Posted by Cbull View Post
That is exactly what I'm thinking. This afternoon I bought a 4" length of heater hose with a 90 in it. Clamped that on, it is now below the surface of the fuselage pointing straight down (still inside the lower cowl) I did a flight around the pattern and no oil. Checked the crank seal and it's dry. As soon as some storms pass I'm going up for a 30 min flight to see how it does.
Pretty sure the plans call for the breather tube to be facing forward. If that is the culprit, I’m sure we’d see many more issues with folks who followed the instructions. My tube is facing forward - I dont have any issues after 180 hours.
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  #17  
Old 08-03-2021, 07:50 AM
FireMedic_2009 FireMedic_2009 is offline
 
Join Date: Nov 2016
Location: Tampa, FL
Posts: 234
Default Oil leak possibly from valve cover

I had a leak on my 3 that I couldn’t figure out. It would have oil on the upper and side of the cowling and drip from the exhaust exit. It turned out the rubber seal on the valve cover was broken. If you have a rubber seal on the valve cover the surface and rubber seal needs to be oil free. If not when You tighten down the valve cover the rubber gasket squeezes out and breaks. If you use a cork gasket you put some oil on it so it doesn’t dry out over time. FYI, the rubber seal/gasket are $15 each compared to cork at about $2 each
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  #18  
Old 08-03-2021, 07:59 AM
Ralph Inkster Ralph Inkster is offline
 
Join Date: Feb 2008
Location: Calgary, Alberta
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Maybe o-ring on C/S prop mounting flange. Prop hub is more pressured in flight when course pitch is set, less so when ground running in fine pitch. Check if front face of flywheel is dry.

Another possibility might be dipstick is popping open, though unlikely
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  #19  
Old 08-03-2021, 08:20 AM
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bkervaski bkervaski is offline
 
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Location: Birmingham, Alabama
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Check the elbows used for your oil cooler... if they are the blue anodized aluminum part, those are prone to hair line fractures and under pressure can spew a lot of oil.
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  #20  
Old 08-03-2021, 11:42 AM
chevytoo chevytoo is offline
 
Join Date: May 2011
Location: Langley B.C.
Posts: 30
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One thing I have done in the past is to put fluorescent dye in the oil, run the engine. Move the aircraft out of the sun, use a black light to search for the leak. Truck shops I know of have the dye and if you are lucky may even be able to borrow their black light. Change the oil after you have finished sourcing the leak. The dye and a black light are also available to purchase from Snap-on Tools.
Ray
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