Oil or water mist out the dipstick tube after flying

[asav8tor]

This falls in the little nuance / zen with your engine theme.

If you open the oil door and unscrew the dipstick after flying, then slowly turn the prop, oil and or water mist will be expelled out the dipstick tube for a couple of turns. This will happen even if you get the oil temps up (210 deg F) during flight.

Thoughts?

(1) Don't do it you are wiping oil off critical areas by turning the prop?

(2) Don't do it you are sucking in just as much or more moisture laden air than you are letting out?

(3) Don't do it's oil mist not water mist?

(4) Good idea, do it?

(5) Doesn't matter you gain nothing and hurt nothing?

[hevansrv7a]

The engine produces water vapor as a normal byproduct of combustion. Some of the water vapor passes the rings and enters the crankcase. The humid air in the crankcase, because it is hot, contains a relatively large amount of water. As the engine cools the water condenses out. Think fog or rainforest.

No amount of getting the oil hot enough matters - new moisture is created.

An engine dehydrator is the only reasonable approach. IMHO. Plug it in as soon as you land and keep it in and on until you are ready to fly.

[AlexPeterson]

Others will of course disagree, but I believe it is good practice (when hangared!) to loosen the dipstick and pull it up and over the filler tube after each flight. There will be a steady stream of water vapor rising for about 5 minutes. This moisture would normally condense inside the engine. I prefer getting rid of it. I'm sure the engine dehydrators are a good idea in most cases.

[Geico266]

Originally Posted by hevansrv7a

No amount of getting the oil hot enough matters - new moisture is created.

The reason for heating the oil is to remove the moisture from the last flight, and to keep it to a minimum. A gallon of fuel produces a gallon+ of water when burned in an engine. Oil can hold or "suspend" moisture. Heating the oil to the boiling point once a flight helps releases the moisture from the oil. Without heating the oil the moisture accumulates to a higher and higher percentage in the oil condensing in the crank case, especially on the top where the cam & cam lifter components sit.

Pulling the dip stick after each flight is an excellent way to allow moisture to escape from the crankcase, year round. Just because you cannot see the vapors when it is hot & humid outside does not mean the moisture is not escaping. I do this every flight and I see vapors everytime. After 5-10 mins. it should be closed up to keep out foreign debris and keep moisture from getting back in when it cools.

Rotax recommends getting the oil to 210F every flight specifically to remove water / moisture from the oil in the crankcase.

A dehumidifier is okay if you don't fly often, but it won't remove water that is suspended in the oil. It only lowers the dew point in the engine air, not the moisture in the engine oil. Only heat to the oil will expell excess moisture.

To answer 8tors questions;

#2. This is why you don't leave the dip stick out all the time, 5-10 mins is sufficent to allow excess moisture to escape.

#3. It is water vapor, not oil smoke. Smoke would not "disapear" a few inches away from the opening. What you are seeing is hot moist air hitting cooler air and it turns into steam.

#5. Allowing the moisture to stay in the crank case can and will cause corrosion on the cam shaft and lifter components for a start.

http://www.barkeraircraft.com/Engine-dryer-kit.html
http://www.flyingsafer.com/test%20report.htm

It's your engine, maintain it how you see fit.