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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> RC Fuels >> fuel, cold, and condensation
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fuel, cold, and condensation - 2/16/2003 8:29:52 AM   
JimTrainor


 

Posts: 1307
Joined: 10/25/2002
From: Ontario, ON, CANADA
Status: offline 		I flew in -10 degree C weather today. The first start was easy, but the engine refused to start after the first flight. Couldn't figure out why, so I gave up. While packing up I noticed that the fuel jug had what appeared to be condensed water droplets all over the inside of the fuel jug above the level of the fuel. It was not subtle, it was very very clear. Many large and small well formed drops.

I am assuming this was water, and I am assuming that this indicates a high moisture level in the air sealed in the fuel jug, and that it may indicate spoiled fuel... which might explain my starting troubles.

But, and I am uncertain if this even possible, it might also simply have been alcohol vapor condensing on the inside of the container. I tried to wipe a bit off the inside of the container to see if I could tell, but it is hard to tell the difference with only a small amount. Methanol does not have a particularly strong characteristic odor.

Has anyone else see this when flying in cold temperatures?
       Post #: 1

fuel, cold, and condensation - 2/16/2003 7:24:22 PM   
Ross Kean



Posts: 686
Joined: 6/4/2002
From: Fredericton, NB, CANADA
Status: offline 		Far more likely that it was condensed droplets of methanol, not water.

Ross

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fuel, cold, and condensation - 2/16/2003 7:52:15 PM   
Waco Driver



Posts: 157
Joined: 1/16/2003
From: Paris, ON, CANADA
Status: offline 		I agree with Ross. Make up some priming mix of 3:1 gasoline : two stroke oil and dribble about 4 drops in the intake. This will give reliable starting to at least minus 14 F, the coldest temperature at which I have flown.

_____________________________

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fuel, cold, and condensation - 2/16/2003 8:27:14 PM   
JimTrainor


 

Posts: 1307
Joined: 10/25/2002
From: Ontario, ON, CANADA
Status: offline 		Great, thanks, I won't dump the fuel just yet.

At my club, the advice was to use some lighter fluid. e.g. "Ronsonol". One way or another, something more volatile than alcohol would seem to be a must.

My second theory is that fuel cooled down during the first flight and that is why it failed to start. Could that be the case? As an alternative to gas, or lighter fluid, would warm fuel be enough?
I may try that, just to satisfy my curiosity.

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       Post #: 4

fuel, cold, and condensation - 2/16/2003 9:19:34 PM   
WMB


 

Posts: 682
Joined: 10/5/2002
From: Great Falls, MT, USA
Status: offline 		I've had similar running problems when flying in temps below ~ 30 F. The needle did not seem to have as much tuning effect at these colder temps. I wrapped the cylinder with tin foil and give a squirt of charcoal lighter fluid in the carb. Doing this took care of the cold weather blues. What is curious though, another flier has no problems at all. Have fun, Mike

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       Post #: 5

Re: fuel, cold, and condensation - 2/17/2003 3:33:46 AM   
tdriver



Posts: 185
Joined: 11/9/2002
From: Athens, GREECE
Status: offline 		[QUOTE]Originally posted by JimTrainor
I flew in -10 degree C weather today. The first start was easy, but the engine refused to start after the first flight. Couldn't figure out why, so I gave up.......[/QUOTE]


3 drops of acetone will start the engine with the first flip!!!

no mater how "bad/cold/humid" the weather is. it amazes me every time i do this.
on cold/humid days,i try 15 seconds with the electric starter and nothing happens,after that i put 3 drops of acetone in the carburetor and they start with the first flip.

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       Post #: 6

fuel, cold, and condensation - 2/17/2003 6:35:51 AM   
JimTrainor


 

Posts: 1307
Joined: 10/25/2002
From: Ontario, ON, CANADA
Status: offline 		Acentone... interesting. That reminded of this web page:

http://www.holdfastmac.com.au/techcharts.html

To my surpise, it said about acetone: "... As an additive to methanol it reduces pre-ignition sensitivity and promotes easier starting under low temperature conditions (up to 10% for these purposes). In small percentages (about 3%) it also reduces methanol's hygroscopic properties. "

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fuel, cold, and condensation - 2/17/2003 9:59:07 AM   
Homebrewer



Posts: 1335
Joined: 12/29/2001
From: Colorado Springs, CO, USA
Status: offline 		Ether (starting fluid). Easy to use, prepackaged, convenient spray bottle. No dripping, no pouring, just point and squirt and guranteed start. I used some to start my .16 on my RC car that had been sitting in my storage unit at 12 degrees F, it started after the 3rd pull on a shot of either into the intake.

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       Post #: 8

cold weather prime - 2/17/2003 7:38:53 PM   
Waco Driver



Posts: 157
Joined: 1/16/2003
From: Paris, ON, CANADA
Status: offline 		The problem with using lighter fluid, acetone, ether, gasoline etc straight, (ie without oil being added), is that an overprime will severely dilute the oil film on the piston/sleeve interface thus reducing the compression needed for cold weather starting. Similarly it will dilute the oil film on the lower conrod / crankpin and can cause galling and rapid wear or seizure if an electric starter is used.

As far as warming your fuel is concerned, by the time it reaches the carburetor thru the small fuel line it will be at approx ambient temp. I store my fuel in my cold garage with no problems.

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fuel, cold, and condensation - 2/17/2003 8:11:41 PM   
JimTrainor


 

Posts: 1307
Joined: 10/25/2002
From: Ontario, ON, CANADA
Status: offline 		I'd like to identify the reasons why my engine would have started easily the first time, but not the second. It is not an engine that has ever failed to start, or been at all balky.

The fuel temperature is one reason, But I agree that the fuel will quickly cool to ambient temperature in the course of filling the tank, priming, etc.

Could the engine temperature itself be the issue? The engine would not have had time to completely cool to ambient temperatures prior to the first start. But would have been quite cool the second time around.

In lieu of fuel additives, would warning the engine itself work?
Anyone tried that?

Although, I can see that an additive seems to be the preferred solution.

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       Post #: 10

cold weather starting - 2/17/2003 8:45:40 PM   
Waco Driver



Posts: 157
Joined: 1/16/2003
From: Paris, ON, CANADA
Status: offline 		Engine temperatures below about 55 F, ( the flashpoint of methanol), are the cause of difficult starting. Warming the engine by holding it in the warm exhaust of a car, pouring hot water over it, heat guns, propane torches etc all work well but are so cumbersome when compared to a few drops of prime mix.

One argument in favour of cold storage of fuel is that needle valve settings do not change once established for the ambient temperature of the day. Fuel stored at room temp gradually increases in viscosity as it cools requiring richening of the needle as the fuel cools. This is more pronounced with fuels containing higher percentages of castor oil.

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fuel, cold, and condensation - 2/17/2003 8:54:01 PM   
JimTrainor


 

Posts: 1307
Joined: 10/25/2002
From: Ontario, ON, CANADA
Status: offline 		aha! Flashpoint of methanal. Okay, I get it now. Now I think I have a feeling for the problem. Thanks Waco.

So I'll experiment with various primes, maybe warming the engine, and read a bit more about the properties of methanol.

Thanks for the tips, everybody.

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       Post #: 12

fuel, cold, and condensation - 2/17/2003 9:20:22 PM   
JimTrainor


 

Posts: 1307
Joined: 10/25/2002
From: Ontario, ON, CANADA
Status: offline 		Acetone flash point: -18 C

http://www.fpm.wisc.edu/chemsafety/Guide/guide/00000007.html

So, I think I'll try some acetone mixed with fuel as my initial prime. Probably start with a low conentration and work up until it is reliable.

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       Post #: 13

fuel, cold, and condensation - 2/18/2003 10:10:59 AM   
downunder-RCU



Posts: 1125
Joined: 12/27/2001
From: Adelaide, South Australia
Status: offline 		Ether flash point: -40

But just because ambient temps are below 55F doesn't necessarily mean hard starts. The temp rise due to compression (not to mention that red hot coil) makes things a bit easier.

BTW Jim...that Holdfast site is part of my web page, glad it's been of some use

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Cold Weather starting !! - 2/18/2003 10:49:46 AM   
jerrysu29



Posts: 260
Joined: 11/23/2002
From: Rapd City, SD, USA
Status: offline 		Out here in South Dakota, N. Dakota & Wyo we use, get this believe it or not !! Works Great first time every time. and you probably have some in your garage at home. WD40 penetrating oil. a little squirt and away ya go.

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       Post #: 15

fuel, cold, and condensation - 2/18/2003 6:20:15 PM   
JimTrainor


 

Posts: 1307
Joined: 10/25/2002
From: Ontario, ON, CANADA
Status: offline 		downunder, Thanks. Yes very useful web page.

Compression and glow plug were fine... even tried a new plug. The glow plug was driven by an "Accu Glow" power panel set at the upper limit of the panel's glow power range. I've started this engine at a few degrees above zero C without problem, so I haven't experienced any particularly difficulties just because temperature was below 55F (~10 C), but -10 C was a problem.

What it "ether" exactly? Other than automotive starter fluid. I'm not familiar with it.

I suppose WD40 has a solvent in it that makes it a viable starting fuild ???

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fuel, cold, and condensation - 2/18/2003 7:08:56 PM   
Sport_Pilot



Posts: 7405
Joined: 1/21/2002
From: Acworth, GA, USA
Status: online 		Not to mention the butane used as a propellent. Suggest mixing about 3% to 5% gas into your fuel. It will also prevent overcooling of your engine which acetone will not do very well.

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       Post #: 17