Taking the Dipstick out after a flight?

Salty said:
liquid cooling sounds great until you figure out you're gonna lose knots by hanging a radiator out in the wind, and useful load due to the weight of the system and water in it.
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I don't think it's quite that cut and dry. Certainly there's some swap space in the decision on the +/- of liquid cooling or not. Even with a current airframe. After all, look at how the Mooney 201 evolved. Some similar work with radiator design and high thermal efficancy cooling would be really interesting.

https://www.kitplanes.com/the-meredith-effect-fact-or-fiction/
 
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Dana said:
Either you force air through a radiator or you force it past the cylinder cooling fins and oil cooler; either way there's cooling drag. Water cooling is more effective, more controllable, and you have more flexibility in how you duct the cooling air.
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Also, you don’t need as much oil volume when you’re not relying on it for cooling.
 
The Meredith effect should work as well for a water cooled engine, shouldn’t it?
 
So....if it's such a great idea....where are all the liquid cooled experimentals?
 
Dan Thomas said:
That crankcase is air cooled. It gets hot, but not hot enough to boil the water off, and it can accumulate water as liquid. Never assume that all the water in that engine is vapor unless it's been flying for an hour or two, long enough to drive the liquid accumulated during warmup into vapor and blow it out, and that takes time. Takes longer in cold weather, and the condensation is much worse in cold weather too.
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So, how much water do you drain from your crankcase when you change your oil??????

The air in the crankcase is near 100% relative humidity. It is saturated.

You do not need to have the oil at over 212 degrees for the water to evaporate. Or haven't you left a glass of water out for a few days and noticed that the level got lower??

The higher the temperature, the faster the water evaporates.
 
Water cooling also maintains a more constant engine temperature, so clearances can be made tighter. Less blow bye, less stuff getting into the oil.
 
Pinecone said:
So, how much water do you drain from your crankcase when you change your oil??????

The air in the crankcase is near 100% relative humidity. It is saturated.

You do not need to have the oil at over 212 degrees for the water to evaporate. Or haven't you left a glass of water out for a few days and noticed that the level got lower??

The higher the temperature, the faster the water evaporates.
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As a mechanic I have drained many crankcases of oil that is the coffee-brown color of oil contaminated with water. Leave it sit for a couple of days, then pour off the oil and find the water at the bottom of the bucket. Water in emulsion like that does not come out of the dipstick hole. Period.
 
I don't do it, but I understand why people are thinking about it. I started using CamGuard after reading everything I could find on it. It is supposed to keep the engine parts covered with oil foam after the engine shuts down to protect the from moisture and rust. I think that is what this thread is all about.
 
I did some calculations, making some very rough approximations, and worked out that the water vapor in the crankcase would condense into less that 1/4 teaspoon of water. That's probably a tiny fraction of what's emulsified in the oil, so I'd say leaving the oil cap off does nothing useful.
 
Dana said:
I did some calculations, making some very rough approximations, and worked out that the water vapor in the crankcase would condense into less that 1/4 teaspoon of water. That's probably a tiny fraction of what's emulsified in the oil, so I'd say leaving the oil cap off does nothing useful.
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I would estimate probably a tablespoon of water condensed on the filler neck of the io 550s I fly. That goes away by removing the cap after shutdown. Anecdotal for sure, but I trust my eyes. Like I said, the amount of steam and water is impressive.
 
I think the best procedure is to drain the oil after each flight, pump dry nitrogen through the engine for 24 hours, seal up the engine, then add fresh oil (with CamGuard) immediately before the next flight.

If anyone adopts this procedure, report back and let us know how many hours you get from your engine.
 
Half Fast said:
I think the best procedure is to drain the oil after each flight, pump dry nitrogen through the engine for 24 hours, seal up the engine, then add fresh oil (with CamGuard) immediately before the next flight.

If anyone adopts this procedure, report back and let us know how many hours you get from your engine.
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draining the oil regularly isn't a great idea either since now you're going to have to prime the oil galleys again on start up.
 
Leave the dipstick in.
If you get stranded in a remote area, you're just going to sit there and beat yourself up that you vented all that water away.

I hope this saves you.
 
Salty said:
draining the oil regularly isn't a great idea either since now you're going to have to prime the oil galleys again on start up.
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Why would draining the engine of oil in the sump drain the oil galleries? Most of them are above the oil level, so would drain with or without draining the oil.
 
Pinecone said:
Why would draining the engine of oil in the sump drain the oil galleries? Most of them are above the oil level, so would drain with or without draining the oil.
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Maybe true. I guess it depends how you are "pumping dry nitrogen in". I was assuming the goal was to remove all the liquids.
 
PaulS said:
I would estimate probably a tablespoon of water condensed on the filler neck of the io 550s I fly. That goes away by removing the cap after shutdown.
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But does it go away by evaporation, or draining back down into the sump?

The 1/4 teaspoon number I gave is for water vapor in the crankcase, not moisture that has already condensed inside.
 
How much moisture are you letting back in from ambient humidity by opening the dipstick?

And no I've literally never done this, ever.
 
Mxfarm said:
@ 100% humidity, how much water is in a cubic foot of air?
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From various sources, blowby gases are 75-85% unburnt fuel/air mixture with the rest combustion products. Exhaust is ~8% water vapor, so I figured rounded up to 10%, times the 25%, to get 2.5% moisture in the crankcase gases... then multiplied that by a estimated 2 cubic feet crankcase volume times the density of saturated steam at 212°F. As I said, a lotta very rough assumptions, but probably within an order of magnitude.
 
Salty said:
draining the oil regularly isn't a great idea either since now you're going to have to prime the oil galleys again on start up.
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Well, naturally you also need to add an electric oil pump that you can run prior to engine start to lube everything.
 
I just want to keep my rust prone cam parked up at the top of the Lycoming terrarium as free of condensed water as possible during the periods I can’t fly every week.

If leaving the dipstick cracked open during those periods helps (again in a dry desert environment), I’m game.
 
What is this humidity everyone speaks so highly of.??

Zeldman, living in the high desert dry air.
 
Half Fast said:
Come visit me in Florida, where the air is so humid you drink it instead of breathing it.
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I grew up in east Texas, did my flight training at Sanford, Fl. My first flying job was at the outer banks, Manteo, NC. I did my time in the humid places. I like my sand and rock front yard...It is so dry here windshield wipers rot away before they get worn out.

However, we have had several thunderstorms in the last few days.... there is actually water in the river...:lol::lol:
 
Half Fast said:
Well, naturally you also need to add an electric oil pump that you can run prior to engine start to lube everything.
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In the car world is the Accusump. Manual or automatic, it stores some engine oil under pressure. Then when you start the engine, it pressurizes the oil system before things start turning and keeps the pressure up until the start occurs.

I never understood why it wasn't used in aircraft where they sit for a while at times.
 
Pinecone said:
In the car world is the Accusump. Manual or automatic, it stores some engine oil under pressure. Then when you start the engine, it pressurizes the oil system before things start turning and keeps the pressure up until the start occurs.

I never understood why it wasn't used in aircraft where they sit for a while at times.
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https://www.oilamatic.com/
https://infinityaerospace.com/product/other/pre-oiler-and-back-up-engine-oil-pump/

[URL]https://generalaviationnews.com/2006/09/08/do-you-need-a-pre-oiler/[/URL]


They exist, but read the article. Not so effective for Lycomings.
 
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