Engine Run Ups

A little tip I read (maybe on here) is to remove your oil filler cap after a flight and watch the steam escape.

I've tried it and it works.
 
I always start to taxi before the oil is in the green. Rotax engines run at 2000 RPM cold, so there is plenty in the prop to pull the plane along while the engine warms up.
 
txflyer said:
A little tip I read (maybe on here) is to remove your oil filler cap after a flight and watch the steam escape.



I've tried it and it works.
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Which, points out that you're really not "boiling off" much if it didn't escape the breather tube in flight and is still there coming out of the oil filler cap after a four hour flight. Hmm.
 
CTLSi said:
I always start to taxi before the oil is in the green. Rotax engines run at 2000 RPM cold, so there is plenty in the prop to pull the plane along while the engine warms up.
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Lycoming pretty much says as long as the engine doesn't stumble when you apply power, that's all the warmup it needs. Continental proscribes a minimum operating temperature of 100F.
 
flyingron said:
Sumping the tanks 5 minutes after fueling is likely to discover NOTHING even if they fillled your tanks with a high concentration of water. It takes quite a while for the water to settle out.
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Have you tested this? In my experience water will settle damn quickly in every container I've ever mixed gas and water in.
 
jesse said:
Have you tested this? In my experience water will settle damn quickly in every container I've ever mixed gas and water in.
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Are you asking if he ever poured water in his tanks to check it?!

The larger the tank the longer its going to take to see, this is common knowledge, its what our mechanics say with my current plane. I've also had a engine failure due to fuel contamination even though I had clean sumps before start.

Most accurate sump is on a plane that has been sitting for hours completely untouched and unmoved.
 
txflyer said:
A little tip I read (maybe on here) is to remove your oil filler cap after a flight and watch the steam escape.

I've tried it and it works.
Click to expand...

Actually, you cannot see steam. What you are seeing is water vapor.

Water vapor is just air with fine water molecules floating in it. The difference is mostly a matter of temperature. Steam exists at 100 C and above. Water vapor at much lower temperature.
 
jesse said:
Have you tested this? In my experience water will settle damn quickly in every container I've ever mixed gas and water in.
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What I have always wondered about is how long it would take for the water to settle to the bottom of the fuel tank, work its way down the fuel line, and to the drain. As a result, I have always wondered whether shaking the wing speeds or delays the ability to detect water. I have never tested it, for obvious reasons.

My practice is to refuel before putting her away. I sump before I take her out. That way the water should be good and settled by the time I sump. If I am refilling right before flying, I will shake the wings before sumping. I figure it can't hurt, because if it hasn't had enough time to settle because I just filled the tanks, shaking the wing isn't going to significantly delay my ability to detect it.
 
PPC1052 said:
Actually, you cannot see steam. What you are seeing is water vapor.

Water vapor is just air with fine water molecules floating in it. The difference is mostly a matter of temperature. Steam exists at 100 C and above. Water vapor at much lower temperature.
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Nope. Water vapor is invisible.

Steam can be seen.
 
PPC1052 said:
Actually, you cannot see steam. What you are seeing is water vapor.

Water vapor is just air with fine water molecules floating in it. The difference is mostly a matter of temperature. Steam exists at 100 C and above. Water vapor at much lower temperature.
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I did not know that. Thanks for clearing;) that up.
 
Man, I've been in the turbine world too long, when I said 200f oil temp, I ment to say 200f CHT.
 
MAKG1 said:
How do you know it's water?

That "stuff" feels a bit greasy.

Assumptions may get you in trouble…
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Well, it certainly looks like some kind of vapor. If it has any water in it, so much the better for the motor after shutdown so I've read. :dunno:

With the humidity we have here, I have considered a dehydrator so that's why it's on my mind. High humidity inside an engine is not good for it. You need to fly often down here or else you risk some rust. If I were in AZ, I wouldn't worry about it. :redface:

Besides, even if it doesn't have any water in it, letting the 'oil' vapors escape from the crankcase can't hurt it can it? ... and it's not too inconvenient to do it. :dunno:
 
txflyer said:
Ah wtf, you see it, you can't see it,

somebody make up their minds cuz there's crap coming out my 710 cap. :dunno::D
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Smoke, most likely. Oil does get really hot on the bottoms of the pistons and will smoke a bit. The case gets full of it. And there's always a bit of blowby, too. And that blowby will contain some water vapor.

Oil doesn't need to get to 212°F to boil off the moisture. Ever seen a pot of water on the stove giving off visible moisture long before it boils? It does, because heating the water raises its vapor pressure and causes it to evaporate faster than it would when cold. It won't just hang around in the crankcase forever until we hit the magic temperature of 212.

Dan
 
Meh. Easy to determine. I'll hold a cold soda can in the "steam" coming out of the cap next time and see what condenses out.

I'm betting water.
 
When I fill up, I always, without fail, sump the tanks for water and make sure it's blue, and smell the GATS jar. Funny thing, I have yet to see anyone else do the same. They always fill up, fire up and go.
 
Aeric said:
and smell the GATS jar.
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Some would not like to do this, but my old crusty CFI told me if I was in doubt, pour a little fuel on my fingers. It will dry to a white residue and not be oily. Just another way to check for jet A.
 
jesse said:
Have you tested this? In my experience water will settle damn quickly in every container I've ever mixed gas and water in.
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It's pretty well been demonstrated with a cut open Cessna tank that it's SLOW.
You might pull something out, but you're deluding yourself if you think you're getting a significant amount.

Ron (The other one) Wattanja has a story on other water in fuel experiences he may choose to relate.
 
flyingron said:
It's pretty well been demonstrated with a cut open Cessna tank that it's SLOW.
You might pull something out, but you're deluding yourself if you think you're getting a significant amount.

Ron (The other one) Wattanja has a story on other water in fuel experiences he may choose to relate.
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Is there a video of that somewhere? I would be very interested in a real test of this versus the dramatically wildly varying opinions that people have that are founded on what some mechanic told them.

I've mixed a lot of gas and water and I've yet to see them separate at any rate other than "fast". I do this weekly.
 
I have seen that video and i think I saw if from a post here, but I can't find it. I wll keep looking though. It was amazing how much water the tank would hold before any it is came out of the sump. IIRC they used red dye in the water.
 
Bill Jennings said:
Some would not like to do this, but my old crusty CFI told me if I was in doubt, pour a little fuel on my fingers. It will dry to a white residue and not be oily. Just another way to check for jet A.
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Less toxic is to pour a drop on a white piece of paper. Gasoline will evaporate quickly and leave little residue. Jet fuel will leave oil.

Avoid getting fuel on your hands. It all contains carcinogens (especially benzene), and "Low" Lead contains quite a lot of TEL despite its name.
 
I own my plane and if I make a quick stop for fuel, for example, I will often do an abbreviated run up while taxing to the runway. Check mixture, fuel, mags, prop, flight controls, etc. I still go through the checklist but I can do it all while taxing or may just have to stop quickly at the run up area to finish. Specially in the hot Florida summers, with an engine that is already hot, I try to minimize extended high power ops on the ground.


Sent from my iPad using Tapatalk HD
 
asechrest said:
Well that's concerning. Does this make a vigorous shaking of the wing before sumping a worthwhile endeavor?
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Agreed! I have no idea of the integrity of this test as I have a hard time with someone purposely designing a fuel tank where the sump is that much higher than rest of the tank. I wonder if this might be from a 140 rather than a 150 and the slope of the aircraft would put the sump at the low point.

I remember the first time I saw that and thinking Holy Bat Droppings.
 
asechrest said:
Well that's concerning. Does this make a vigorous shaking of the wing before sumping a worthwhile endeavor?
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The shaking is generally recommended to move already coalesced water trapped in the ends of the wings down to the sumps. Usually associated more as a problem with bladder tanks with wrinkles than smooth bottom tanks in wings but some wing tanks " jump over " ribs and what not.

Later aircraft have sumps at every low point to satisfy the liability lawyers, see late model Cessnas for examples. Buku sumps. Everywhere.

My 182 has big long range bladders and one definitely has a wrinkle with only a single sump at the wing root. I shake a bit for "the wife and the dog", but shaking if the water is still suspended above the bottom of the bladder doesn't do much of anything.
 
That would not be good from what they showed in the pictures.

I'm hoping the tail down angle of my wings along with the sumps being aft, there's no way for water to 'trap' around the pickup like in that 150.

I've never sumped any water to speak of, but I keep mine hangar'd. I should install the monarch caps someday ... probably when a bladder goes bad.
 
rbridges said:
that's pretty interesting. Do you think the position of the tank is accurate? They placed the gas tank flat. Shouldn't the wing's slight dihedral effect allow the water come over the rib a little quicker? maybe not since the stained area matched the water pool.

Still pretty neat to see.
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I would agree that there is a Paul Harvey side to this but still makes you go Hmmmm?
 
There's not much dihedral in the 150 wing and I have to believe he propped the tank to simulate how it would sit. There are two sets of similar experiments done with in situ tanks on real 150s on that site as well.
 
denverpilot said:
The shaking is generally recommended to move already coalesced water trapped in the ends of the wings down to the sumps. Usually associated more as a problem with bladder tanks with wrinkles than smooth bottom tanks in wings but some wing tanks " jump over " ribs and what not.

Later aircraft have sumps at every low point to satisfy the liability lawyers, see late model Cessnas for examples. Buku sumps. Everywhere.

My 182 has big long range bladders and one definitely has a wrinkle with only a single sump at the wing root. I shake a bit for "the wife and the dog", but shaking if the water is still suspended above the bottom of the bladder doesn't do much of anything.
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We have basically the same plane, and I have the long range bladders too.

Have you ever got any water out of yours after a shake?

Mine wing has a more pronounced angle backwards where the water should settle all along the aft bottom of the bladder. My sumps are at the wing root too and I'm assuming all the way aft in the bladder. But if there are ripples in the bladder flooring, or over ribs, I can see where there could be 'traps' outward along the back low points. :confused:
 
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