Evaporated moisture from your oil

Patman

Staff member
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21,989
Location
Oakville, Ontario
I am curious, when the moisture in your oil evaporates, how does it escape out of your engine? I'm assuming most engines are pretty well sealed up, otherwise we'd see a lot more silicon in the oil from dirt getting in there if it was windy out.
 
Messages
209
Location
Spring TX
quote:
Originally posted by Patman: I am curious, when the moisture in your oil evaporates, how does it escape out of your engine?
That's what the PCV system is for (Positive Crankcase Ventilation). Filtered air from the air intake comes into the engine on one side, and the blowby, moisture, etc. in the crankcase is vacuumed out on the other side throught the PCV valve and burned in the engine. That's why you have to keep that valve clean.
 
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4,838
Location
Lakeville, MN
Yep, that is part of the job of the PCV system. Pull any vapors - oil or moisture - and introduce them into the intake side of things to be burned in the combustion process. That is how all the air introduced to the engine stays "clean" - its sourced from after the air cleaner. Thus, when a PCV system gets clogged, thats when we see oil with water in it and get reports of milky sludge buildup.
 
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4,478
Location
Southern California
By the time the engine oil is up to normal operating temperature, any liquid state water in the sump will have been vaporized, drawn through the intake system via the the PCV sytem, and expelled out the exhaust pipe.
 
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4,838
Location
Lakeville, MN
Also depends on outdoor temps, how cold the engine and lubricants are, driving style, particular engine, etc... In other words, tough to give a fixed answer - depends on too many variables.
 
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1,034
Location
GA, USA
Would you guys agree that once the oil temp has reached 100°C there probably isn't anything in the engine cooler than that temp for moisture to condense on? [I dont know]
 

Al

Messages
19,199
Location
Elizabethtown, Pa
quote:
Originally posted by Blokey: Would you guys agree that once the oil temp has reached 100°C there probably isn't anything in the engine cooler than that temp for moisture to condense on? [I dont know]
I'd agree. The water will be gone by the time the oil temperature hits 100 C. Remember that the oil temp lags the water temperature. So once the water temp is up to temp you will need to give the oil say another 10 minutes or several miles for the oil to get up to temp. [Smile]
 
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345
Location
Northern California
Someone here, I believe, once said that the oil splashing on the hotter parts of the engine, like the bottom of the pistons, would probably vaporise the oil quickly. This would seem to make the process only take a short time. On the other hand the engines that have the milk like water and oil mix stuck under the valve covers seem to retain that mix for quite a while. So I guess I don't know but two ideas.
 
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