Taking the Dipstick out after a flight?

SixPapaCharlie said:
Is it bad if I don't do this?
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FWIW: you'll find a number of tidbits like this floating around over the years but few have any real/proven affect in the overall picture. On the other hand flying the aircraft for a solid hour every 30 days does help prevent internal corrosion issues and is what is recommended by the OEMs. I've found that if one were to simply follow the basic OEM recommendations on the operation of an aircraft you'll money ahead and is what I would recommend to any owner who wanted to get the most out of their aircraft and its components.
 
Dan Thomas said:
The PCV system relies on intake vacuum to make it work.
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Of which there is plenty once you ease back on the throttle to descend to an airport and taxi to your final on the ground destination. (Unless you fly for a jump operation.)
And, what you care about is cleaning out the bad stuff before you shut down.

Dan Thomas said:
Can someone tell my why that vapor will come out of the dipstick tube but refuses to come out of the breather?
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The breather is about a mile long?
With the dipstick stuck the system is "dead ended" and there is no flow?
With just the breather, you are relying on diffusion. With a couple of holes in the system (breather and dipstick) there is at least a potential for convection on some applications. I would think.
 
Dan Thomas said:
Can someone tell my why that vapor will come out of the dipstick tube but refuses to come out of the breather? Both of them lead directly into the crankcase, with no restrictions anywhere.
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I'm a renter, and was asked to do this by the place I rent from. It's not a hard fast you have to do this rule, but more of a this is what we would like you to do. They have about 15 or more newer Cirrus. I was a little skeptical until I did it on a hot engine. The cap is obviously hot, I undo it, pull the dip stick out a couple inches and a steady 'waft' of steam rises out of the filler tube. As I said before, it is impressive and does this for about 5 or more minutes.

I take the airplanes fairly frequently on overnight trips. Sometimes after a longer ride, I'll need to use the facilities or be otherwise distracted and forget to pull the cap off. The next day I'll get to the airplane, pull the cap to check the oil, the filler neck and dip stick will be covered with water. The filler necks and dipsticks on these aircraft used to have a tan oily emulsion on them, that doesn't happen anymore. This is across the engine types, the continentals, I0-550, IO-360 and the Lycoming IO-390 .

As to why the steam rises out of the filler, I suspect it's because heat rises and this the high point on these engines. I'm pretty sure Cirrus routes the breather to the bottom of the cowling. So without the active pressure of blowby, whatever steam is left in the engine after shutdown stays there.

I get the skepticism, but until you try it out, you won't know.
 
PaulS said:
I'm a renter, and was asked to do this by the place I rent from. It's not a hard fast you have to do this rule, but more of a this is what we would like you to do. They have about 15 or more newer Cirrus. I was a little skeptical until I did it on a hot engine. The cap is obviously hot, I undo it, pull the dip stick out a couple inches and a steady 'waft' of steam rises out of the filler tube. As I said before, it is impressive and does this for about 5 or more minutes.

I take the airplanes fairly frequently on overnight trips. Sometimes after a longer ride, I'll need to use the facilities or be otherwise distracted and forget to pull the cap off. The next day I'll get to the airplane, pull the cap to check the oil, the filler neck and dip stick will be covered with water. The filler necks and dipsticks on these aircraft used to have a tan oily emulsion on them, that doesn't happen anymore. This is across the engine types, the continentals, I0-550, IO-360 and the Lycoming IO-390 .

As to why the steam rises out of the filler, I suspect it's because heat rises and this the high point on these engines. I'm pretty sure Cirrus routes the breather to the bottom of the cowling. So without the active pressure of blowby, whatever steam is left in the engine after shutdown stays there.

I get the skepticism, but until you try it out, you won't know.
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And after you try it out you won’t know.
 
What indeed. I thought the topic was preventing corrosion. Even an inch of water in a dipstick tube isn’t causing corrosion on the important parts. Removing it isn’t evidence of corrosion protection.
 
If it were my own planes, I would take the time to do it. It's highly unlikely that "an inch of water" in the oil filler pipe, or even less, is going to remain in the filler pipe considering said water will be subject to the effects of gravity. Plus having condensed water anywhere in the engine pretty much guarantees the relative humidity in the totality of the engine will stay at 100% until the water evaporates. So from a purely speculative standpoint, I would feel pretty comfortable that removing any water from inside the engine lessens the issue of internal engine corrosion. But it's certainly not an absolute, I know that.

The obvious benefit in the airplanes I fly is the oil filler pipe doesn't fill up with brown crap from water contaminated oil. A win in my book. But if someone doesn't believe this, or doesn't want to do the extra step, that's fine with me.
 
I do it, a lot of vapor comes out. Can't hurt, and don't cost nuthin'. I did make the mistake once of doing a brief ground run at one point, and shortly thereafter coincidentally had to change a pushrod seal. I was amazed at how much water I found in the valve cover.
 
On first reading I thought he was asking if we were going to take him out to dinner after the flight.
Dave Theisen said:
I’m late to the thread, but I was going to tell @SixPapaCharlie that once the dipstick has been removed from the left seat, he should be good to go. :)
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Icelan:
He checks his sanity with a wrist watch!

Jack Braddock:
What do you check yours with, a dipstick?
 
Now I gotta go watch Blue Thunder again.
 
Chip Sylverne said:
I did make the mistake once of doing a brief ground run at one point, and shortly thereafter coincidentally had to change a pushrod seal. I was amazed at how much water I found in the valve cover.
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Yup. And how much "steam" would it take to make up that much water, times the number of rocker covers, plus the water in the case?

If you pulled a cylinder off after that brief run you would find water droplets between the piston and cylinder wall, too. BTDT.
 
Each gallon of gasoline burned produces around 7 lbs of water.
I am going to fly over California as they are so short of water & I want to do my part to help their drought.
I know they’ll want to cover my costs out of gratitude, does anyone know the governor’s mailing address?
 
Actually, that's a good point. Maybe there should be a public service message asking everyone in CA that still has a car with an actual engine in it to idle if for a few hours, to build up enough humidity so it'll rain more.
 
Albany Tom said:
Actually, that's a good point. Maybe there should be a public service message asking everyone in CA that still has a car with an actual engine in it to idle if for a few hours, to build up enough humidity so it'll rain more.
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And remove the catalytic converter to reduce the amount of CO2 emitted.
 
Salty said:
What indeed. I thought the topic was preventing corrosion. Even an inch of water in a dipstick tube isn’t causing corrosion on the important parts. Removing it isn’t evidence of corrosion protection.
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Finding water in dipstick tubes is normal in colder weather. That tube, if it's long enough and sticks out far enough, gets a lot colder than the rest of the engine, and water condenses in it. One regularly sees rust inside the neck of the oil tank on a small Continental. You would find rust in a Lycoming's tube too, if it wasn't plastic.
 
Zeldman said:
I thought we had determined that spraying the engine down with cool water after a flight prevents condensation from forming inside the engine...
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Nope, that would do the opposite. You need to make sure the engine never cools.
 
For the folks on here who rent, do you just leave the dipstick out? Or?

What about the owners? Do you leave it out until your next flight? Or are we talking about just a few minutes while you put away the plane and stuff
 
172andyou said:
Nope, that would do the opposite. You need to make sure the engine never cools.
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Let’s see - assuming 2000 hours to TBO and 10 gph, that’s only a 20,000 gallon fuel tank. At, say, $6 per gal, that’s $120,000. Seems like a reasonable method.
 
Half Fast said:
Let’s see - assuming 2000 hours to TBO and 10 gph, that’s only a 20,000 gallon fuel tank. At, say, $6 per gal, that’s $120,000. Seems like a reasonable method.
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Running the engine at idle speed doesn't accumulate on the tach. It definitely doesn't use 10gph. Gas hasn't always been this expensive.
 
Tantalum said:
For the folks on here who rent, do you just leave the dipstick out? Or?

What about the owners? Do you leave it out until your next flight? Or are we talking about just a few minutes while you put away the plane and stuff
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For me it depends. If I have the plane away, I leave it out until I get everything squared away, usually at least 10 minutes, then replace it and button things up. If I am dropping the plane off back at home field, they usually come and pop the stick out. It's pretty much turn key service, I just take my stuff and leave.
 
I do it. Lots of steam comes out of my IO550.

Even more is released if you wait a bit, then turn the prop by hand. But turning the prop is a bad idea - if the engine started you could get killed, and no amount of steam is worth that.
 
I have 520’s and do it at the end of each flight for about 30 mins or so while I wipe down the leading edges, I figure it can’t hurt and am surprised by the amount of steam that comes out.
 
Let's see, 1 quart of water for every gallon burned. So after a couple of hours at 13 GPH, the water is pouring out of your engine. :D

Most of the water goes out the exhaust. Remember the contrails of the bombers in WWII photos? That is the water vapor.

Air can only hold so much water vapor. So there is a limit as to how much there is in the crankcase. And remember, there is blowby and a breather, so water vapor, along with some oil vapor is constantly leaving.

That said, the air in the crankcase is likely to be fully saturated, so as it cools, some water will condense and be in the engine. So removing the dipstick or opening the oil filler will let some of that hot saturated air out. Even better would be to blow some dry air into the the dipstick or oil filler to drive out the saturated air through the breather. Some people have set up a small dehumidifier to do this.
 
Ghery said:
Law of primacy. My original CFI did not teach me to do this 22 years ago and he was a former airline pilot. I haven't worried about it and the club hasn't lost a motor due to water in the oil as long as I've been a member (22 years). YMMV.
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Was he an airline pilot on piston engined airplanes?

The big radials had an oil tank, there was very little oil in the engine. And water in the oil tank was not that big of a deal (I mean a bit of condensed water).
 
When I land I open my cowl to let it cool and crack the dip stick, close them back up before putting in the hangar. Does it help, don't know about the dip stick thing but I'm sure letting it cool faster helps battery/wires/electronic.
 
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Pinecone said:
Air can only hold so much water vapor. So there is a limit as to how much there is in the crankcase. And remember, there is blowby and a breather, so water vapor, along with some oil vapor is constantly leaving.

That said, the air in the crankcase is likely to be fully saturated, so as it cools, some water will condense and be in the engine.
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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.

If GA was much bigger we'd have liquid-cooled engine by now, with their tight clearances, and some form of PCV, maybe driven by the exhaust from the vacuum pump, filtered and pressure-relieved and injected into the crankcase, and the breather outlet air let into the engine intake via a PCV valve.
 
Meh....where are all the experimentals with liquid cooling?
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.

If GA was much bigger we'd have liquid-cooled engine by now, with their tight clearances, and some form of PCV, maybe driven by the exhaust from the vacuum pump, filtered and pressure-relieved and injected into the crankcase, and the breather outlet air let into the engine intake via a PCV valve.
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I’ve toyed with the idea of making a fitting to go on the end of my compressor hose, tgat goes into breather tube or over it, open oil filler. Compressor has water separators and desiccant filters for painting.

set the outflow it to like 10lbs so it’s just a breathe of air at full boar… let the tank fill, unplug it and head out and get 20 mins or so of dried air going through the engine…
 
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For reference, IIRC my original CFI flew turboprop aircraft when he flew for an airline. I'd ask him, but he passed away a number of years ago.
 
Checkout_my_Six said:
Meh....where are all the experimentals with liquid cooling?
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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.
 
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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Maybe, but the Rotax engines I flew in the Tecnams had liquid cooling. I think the radiator drag may have been offset somewhat by having a dry sump with a separate oil tank. The engine profile was lower since there was no need for an oil pan.

And the weight was still lower than a Lycoming with equivalent HP.
 
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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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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