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RV12is - Oil Can - evidence of water

richpezz

Member
I reach out to RV builders again to determine if I have a big problem OR no problem at all.

My first engine run (912is) was uneventful as all temps / pressures stayed well within the "green". I ran the engine for about 10 minutes.

24 hours later I checked the oil can for the first time after the engine run and noticed a "milky" white substance on the cap and evidence of water (small droplets) on the inside of the oil can throat (see attached pics).

Is this expected OR is this an abnormal situation that needs further investigation. NOTE: The oil on the dipstick showed NO evidence of water.

Thanks for any input.

Rich Pezzullo
 

Attachments

  • Oil Can Cap - milky substance.jpg
    Oil Can Cap - milky substance.jpg
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  • Oil Can Throat - water droplets.jpg
    Oil Can Throat - water droplets.jpg
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My guess is you did not get the engine up to full temperature and for a long enough period of time to "boil" the moisture out of the oil. Oil needs to run hot (+200F) for a lengthy period of time. New engine has a lot of blow-by on piston rings, until they seat, which makes moisture (combustion produces CO2 and water) that mixes with the oil.
 
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No problem

It shouldn't be a problem once you start flying and the oil temperature gets hot enough for an extended period to vaporise the water that is a by product of normal combustion.
The Rotax engine operation manual provides detail guidelines on oil temperature and duration requirements.
A ground run of 10 minutes would definitely not get the oil hot enough to eliminate the water, so that condensation is not unexpected. I wouldn't worry about it. Just get flying when you can!
 
Rich,

I see from your profile you live on the coast. Your issues are probably due to high humidity. I think the other guys are right about getting your oil temp up. ROTAX documents talk about needing an oil temp above 212F to keep moisture out.

Rich
 
Look at what the participants on the thread are flying, very few -12's. Only the -12 use the Rotax engines. I believe the Rotax is a different oiling system vs Lycoming / Continental and others.

It might be worth questioning if what they need to do applies to us.

Posts 2, 3, and 4 above are spot-on for Rotax 912 series engine...
 
Rich,
If I do a short Ground run to check something I too will had the moisture on the bottom of the cap and the oil tank neck like you showed in your oil tank neck. I try to avoid those short ground runs because I know the moisture is not good, but if it’s done occasionally I think you will be fine.

Running with oil temps 200 degrees plus for an hour is a good thing for your engine. Regular flying is good for the engine overall and of course long periods (6 weeks or more) of sitting inactive not so good. These machines are happiest when flying.
 
From the Rotax Operators Manual for 912 Series:

"Avoid operation below normal operation oil temperature
(90 to 110 °C / 194 to 230 °F), as possible formation of
condensation water in the lubrication system badly influ-
ences the oil quality.
To evaporate possibly accumulated condensation water,
at least once a day 100 °C (212 °F) oil temperature must
be reached."

I aim to make each flight at least 30 minutes, or preferably an hour or more. I usually fly 2 or 3 times per week if the weather is OK and have never observed condensation in the oil (912ULS).
 
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Posts 2, 3, and 4 above are spot-on for Rotax 912 series engine...

Jim,
reread my post again. I was referring to the post from jrtens talking about a "recent thread". That recent thread is 7 pages long discussing venting the oil system after a flight. If you look at the participants signatures only a couple own RV-12 models.
 
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