Draining fuel and running the engine until it quits
 

At the end of a training session, when it's time to store the plane away, my instructor has me pump any remaining fuel from the tank and then run the engine until it quits in order to use any remaining fuel left in the lines and engine.

Is this what most people do and what's the purpose?

Also, is it okay to re-use the fuel pumped out? I would think it picks up air from vibration and dust from being pumped in and then out and then in again.

Thanks in advance.

RE: Draining fuel and running the engine until it quits
 

I do it.'

I reuse the fuel

RE: Draining fuel and running the engine until it quits
 

Just like PilotFighter, I do it all the time. At the end of the day I pump any remaining fuel out of the plane and back into my fuel cans in my flight box. I start the plane and run the fuel left in it out. I've been doing this for 12 years and have never had a problem with fuel going bad or getting contaminated.

Ken

RE: Draining fuel and running the engine until it quits
 

Good question... I've heard of people doing it but I guess I just don't know why. I would understand doing it if you weren't going to fly that plane for a long time but I know guys that do it every time they pack up and leave for home. Even if they come back out the next week. So for those of you that do it, why?

RE: Draining fuel and running the engine until it quits
 

The reason you do it is to get the alcohol out of the engine. Alcohol holds water and water... causes rust. That's the engine part. For the tank, well, the same thing can apply. Remaining alcohol with a vent to the outside can accumulate water. And, it can also drip out on you wife's new carpet.. if, of course, you are married. If you are not, then well, she won't care, will she.

CGr.

RE: Draining fuel and running the engine until it quits
 

Got it, thanks.
I have caps that I use to cover my muffler and carburetor when storing the planes between flights, so is that doing the same thing? They completely close them. I guess if there was a leak in the line it would still get moisture in, but that never happens... ;)

RE: Draining fuel and running the engine until it quits
 

I ruined an engine with this philosophy. I didnt bother with after flight defuel and maintenance because I was going to fly with my instructor the next weekend. Well, weather, and schedule conflicts kept us apart till the next flying season 6 month later. Enough moisture had gotten into my engine that the bearings rusted out. (Or so I assume, it was my only Evolutions and Im still wondering why everyone tells me it shouldnt have gone bad)

RE: Draining fuel and running the engine until it quits
 

Also a good time to practice a deadstick landing. Just fly the last tank dry.

Then the tank is empty and the engine is run dry.

RE: Draining fuel and running the engine until it quits
 

We were just talking about this at the field today. One guy said he heard that the combustion products which reach the gas tank through the vent line are enough to contaminate your fuel supply. However we both still drain out tanks back into our fuel reservoirs. Thinking about it now, either way that fuel will run through the engine, so I don't understand the difference.

I drain my fuel back into my supply (to remove the possibility of water accumulation, and so when I turn my plane upside down, or nose down to carry it around, fuel doesn't pour into the engine). I run the engine until it's totally dry, and use a few squirts of after run oil. This is what it says to do in my OS 46AX manual, and that's what I do. I have the best running engine at my field, hands down, and it burns a gallon of fuel per week (has some hours on it). It starts with one, two flips of a stick at most, so I intend on continuing this practice.

RE: Draining fuel and running the engine until it quits
 

Nitromethane left in the engine can be very corrosive.

RE: Draining fuel and running the engine until it quits
 

I also pump the remaining fuel back into my fuel jug and reuse. To costly to throw out and I have never had a problem with this practice. Then start the engine and run dry and add some afterrun. Real good practice to get into.

Curt

RE: Draining fuel and running the engine until it quits
 

Picked up some good tips from asking this question in this thread. I didn't even know there was such a thing as after run oil. So when you say a few 'squirts' do you just add a few drops to the carb after running the last few drops of glow fuel out of the engine? What's a good brand?

Also, is it true synthetic glow fuel won't leave that rust colored residue on the outside of the engine?

RE: Draining fuel and running the engine until it quits
 

I've always drained and ran dry...yes you can get stuff in your fuel jug....I can't swear to ya where the stuff comes from...off the pick up line? from the cap? or from the tank...moisture in the fuel can come from contensation going from hot humid summer weather with the cap open ( lines in the cap for refueling is still open to atmosphere) to cool garage floor or worse air conditioned car...
When the fuel jug gets low I'll look in the jug and see how much contamination, if any, there is. If there is some I won't use the last bit of fuel...And never ever pour the remains from one jug of fuel to a new jug.

RE: Draining fuel and running the engine until it quits
 

I just use the hobbico brand, my lhs has them in a box at the checkout desk. I do 3 to 4 drops down the carb and hit it with the starter for a couple seconds to get it thrown all around. I do the same with my nitro cars too. If you use a nice filter setup for fueling, you shouldn't have to worry too much about getting trash in your fuel.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJ811

RE: Draining fuel and running the engine until it quits
 

I use a little more after run than a few drops; basically I put the throttle on idle and fill the carb. Turning the prop sucks it all right in, and I turn the prop over maybe 6 or 7 times to let the insides of the engine get covered. Right now I have Hobbico brand, 'cause I added it on to a Tower order. You can use air tool oil or automatic transmission fluid for cheaper, but so far the $3.00 bottle has lasted many days at the field and isn't close to being empty yet.

And yes, synthetic oil doesn't varnish like Castor does. I knew about the varnishing, but hadn't actually seen it yet. The varnish will also form on the insides, too. It's protection for a while, but I guess at some point it needs to come off?

RE: Draining fuel and running the engine until it quits
 

I think the idea is pretty much established, but one thing no one has mentioned: When you leave fuel in the engine of the tank for an extended period of time, substances that can evaporate do, and you're left with a thick chewing-gum substance that is very difficult to remove. I don't know how long this takes, weeks? months? years? but it happened in a plane and engine I bought second hand....... some nasty stuff man. I'm pretty sure I had to replace the tank. Fuel and alcohol wouldn't cut the stuff.


Oh, and I run mine dry after every flying session and give it a couple spins with the starter and glow driver just to make sure. I also return the fuel to the jug. I figure if there's any debris in it, I pump through a filter into my plane anyways.

RE: Draining fuel and running the engine until it quits
 

Where do you squirt the after run oil? Tower Hobbies says not to put it in the carb as it may cause the O-rings to deteriorate.
They say to pour into the exhaust port - doesn't that require you take the muffler off? Or the glow plug hole.

http://www3.towerhobbies.com/cgi-bin...&I=LXL391&P=ML

RE: Draining fuel and running the engine until it quits
 

I've been dripping it in the carb for years now and have not had a problem at all with "O" Rings.

RE: Draining fuel and running the engine until it quits
 

Instead of using after run oil, how about adding a cap full of pure synthetic lubricant to a gallon of fuel -synthetic fuel at that, to avoid the gumming in the engine from castor oil?

If anyone does this, please recommend a good synthetic fuel and lubricant. From a quick search on the web, I see Morgan Fuel Cool Power ingredients seem to fit the bill.

Much appreciated in advance.

RE: Draining fuel and running the engine until it quits
 

Cappaj1,
If you use Morgan fuels you don't need to add or use after run oil. They already blend it in to their mixtures. I have engines that have been stored for 5+ years with nothing more than running the fuel out of them and then storing them, zero rust in them.

Ken

RE: Draining fuel and running the engine until it quits
 

Thanks, Ken,

They have a selection of different fuels. If you don't mind, which one do you use, the Cool Power?

RE: Draining fuel and running the engine until it quits
 

I run Cool Power 15% in every glow engine I own, with the exception of my YS engine. In that I use Cool Power 25%

Ken

RE: Draining fuel and running the engine until it quits
 

How much does the Cool Power 15% cost right now, if you don't mind? I realize the cost is due to go up drastically from the nitro methane shortage but just to get an idea.

RE: Draining fuel and running the engine until it quits
 

It depends a lot on where you buy it, and how much you buy. I can get it for $13/gallon if I buy a case, but that's in Dallas. The shop where I usually buy it at runs $15.99/gallon.

Ken

RE: Draining fuel and running the engine until it quits
 

The LHS here sells it for $30/gal (15%).

RE: Draining fuel and running the engine until it quits
 

I see tower hobbies has it for $90/4gallons which is alot more, so it sounds like fuel is one of those things best purchased locally.

RE: Draining fuel and running the engine until it quits
 

Has anyone any experience with Wild Cat glow fuel? It sounds like another premium fuel but you can't believe the ads I guess.

http://www.wildcatfuels.com/fuel_premium.htm

RE: Draining fuel and running the engine until it quits
 

I run Wildcat in both my planes and cars, its good stuff. The pricetag is right too, for now.

RE: Draining fuel and running the engine until it quits
 

I have used the following brands and all have performed very well: Cool Power, Magnum, Omega, Powermaster, Ritch's Brew, Wildcat.

People in our club also use Sig and Byron's fuels with good results.

As long as the oil type and percentage are correct for your engines (see the manual), I think the majority of fuels are very good.

RE: Draining fuel and running the engine until it quits
 

Definitely buy fuel locally if you can. If you have it shipped, you have to add a "hazardous materials" shipping fee on top of the price.

RE: Draining fuel and running the engine until it quits
 

That's the free market society. They can set their price at whatever they want to. But at $30/gallon they are asking for and getting over 100% profit over thier cost. If everybody there didn't pay that price they would be forced to lower it.

Ken

RE: Draining fuel and running the engine until it quits
 

Does anyone know what percentage of Nitromethane CoolPower has?

RE: Draining fuel and running the engine until it quits
 

I realize that most people answered that they reuse the fuel pumped out and that's what I plan on doing as well, but I just checked Morgan Fuel Cool Power FAQ and it states:

Q: "Should I pour the unused fuel from my tank back into the fuel jug?

A: No!

As mentioned in the question above about shelf life:

A quick way to ruin a gallon of fuel is to drain your tank at the end of your flying day back into the fuel jug. What is happening is that your fuel is picking up moisture from the pressurized tank. The carburetor is sucking in humid air and after combustion the moisture laden air is entering into your tank via the tube from your muffler. When you return the fuel from your tank to your fuel jug you are contaminating the rest of the fuel in the jug.

My recommendation is to run your tank dry at the end of the day, but whether you do that or not don't return the fuel from your tank to your fuel jug. "

Of course to me and sounds like most people that's not practical and of course the manufacturer would like you to use as much of their fuel as possible.

Bottom line, I have come to the conclusion the best real world solution is to try and fly until almost all the fuel is used (or to practice dead stick landings, until ALL the fuel is used) and then pump any remaining fuel, which should be a minimum amount, back into the jug.

RE: Draining fuel and running the engine until it quits
 

There's a very good reason why you should run the engine dry at the end of each day's flying. Methanol soaks up water from the air like a sponge and water causes rust. I think everyone knows you can pinch the fuel line, or even remove it, when the engine is at idle and it'll keep running for several seconds. That's because at idle the crankcase fills up a little with raw fuel because there's not enough air flow (turbulence) inside the crankcase to sweep it up into the cylinder. To get rid of this excess fuel you should run the engine at high speed, even full throttle, then pinch or remove the fuel line. The engine will stop almost straight away but as it runs down to a stop it's still sweeping up tiny bits of fuel that aren't enough to actually burn so they get swept out the exhaust. Now all that's left inside the engine is oil.

So, after run oils. Synthetic oils as used in fuels tend to slide off metal surfaces like water off a duck's back leaving the metal exposed to air which will have some moisture in it. Once again, rusting. After run oils are different to synthetics because they have a special property that makes them like to stick to metal so air (and moisture) can't get to the metal. No rusting. But most after run oils won't mix with methanol so they can't be added into the fuel to make sure it's covering every part inside the engine. Except for one extremely good after run oil. Castor :). It also happens to be an exceptionally good lubricant so you get the best of both worlds.

And one hint. If you run the engine dry at full throttle by pinching the fuel line then keep it pinched for a few seconds after the engine has stopped. This gives time for the pressure that's built up in the nearly empty tank to drain back through the muffler. If you let the line go as soon as the engine stops then the pressure in the tank will force some unwanted fuel back into the carb.

RE: Draining fuel and running the engine until it quits
 

Thats actually an exageration, it only soaks up water it comes in contact with. If you put humid air in a jug of methanol it will eventually asorb the water, but it takes time. Morgans has a point about the fuel getting contaminated from the pressure tap line, but they were wrong about the moist air, even with 100% dry air the combustion of alcohol will produce lots of H2O vapor. It can be a problem if you were to say only fly a few minutes a day and pump back a nearly full tank back in the fuel jug for each short flight. But I have no problem with normal usage.

RE: Draining fuel and running the engine until it quits
 

Running a 4 stroke dry does little good in so far as keeping it from corroding. A four stroke will always have a fair amount of fuel and exhaust residue in the crankcase, even if run dry. That is why, IMHO, on fourstrokes, use after run oil and put it into the crankcase. Putting it in the exhaust or carb will do little if any good as it will not get to the main bearings where the rust problems will usually start. Not just a drop or two but about a teaspoon full then manually rotate the prop and engine to make sure the oil gets to all the bearings to displace any fuel. As mentioned above, it is the nirto component in the fuel and oxygen that will do most of the corrosion problems so coat the bearings with after run oil to displace the nitro laden fuel residue.

RE: Draining fuel and running the engine until it quits
 

But likely not totally empty. I am very religious about pulling the fuel line off the carb, priming the engine and hitting it with the starter again - several times. In fact, I have a small quantity of castor-only fuel I use to do this.

If you simply shut off the engine using the throttle, there will surely be a bit of raw fuel in the crankcase. Not good for the steel crank or ball bearings - especially if you use an all-synthetic lube.

Be careful though... Once I pulled the fuel line off and restarted the engine. There was still about 1/4 tank of fuel and the muffler pressure line was still hooked up. I couldn't figure out why my engine kept running and running and running - and throwing fuel everywhere. The pressurized tank was spraying fuel out the disconnected fuel line and some of it was getting sucked directly back into the carb across a 1" gap of open air.

An after-run oil is also helpful, no matter what the various fuel manufacturers will tell you. You can make up an effective home brew after-run concoction using 50/50 automatic transmission fluid and lighter fluid. The engine will fire on this mixture and the ATF gets distrubuted all through the innards of the engine. In fact, that expensive commercial after-run oil you use may be exactly the same thing you can make yourself.

RE: Draining fuel and running the engine until it quits
 

Disagree. I don't think nitro is corrosive. The methanol we use will absorb water out of the air. The water is what causes the corrosion. You want to get the methanol out of the engine and coat it with a protective film of castor oil.

RE: Draining fuel and running the engine until it quits
 

Cappa, I read on one of the engine mfg. sites that they mean do not inject the afterrun oil directly into the fuel access at the needle valve. That assembly must have some o-rings. Through the carb is the accepted approach. They also said a few drops will do nothing to protect the engine, they recommend at least a teaspoon.

RE: Draining fuel and running the engine until it quits
 

You are right. It is filled with air. But not a drop of useable fuel.

For those of you running the engine dry on the ground, do it then wait for a minute. Then hook up the glow plug and spin the engine again. Quite often they will fire again with the fuel that is still in the engine.