Moisture in fuel ??  
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> RC Fuels >> Moisture in fuel ??
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Moisture in fuel ?? - 9/8/2002 5:11:57 PM   
jdan


 

Posts: 91
Joined: 12/17/2001
From: media, PA, USA
Status: offline 		How can you tell if you have moisture in your fuel? I just started a new gallon of Mach 7 ( two months old) I tried it in two different planes. After about two minutes of flying ,the engine goes rich.
The only thing that corrects it, is to change the glow plug.After one good flight, it's the same thing all over again.
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Moisture in fuel ?? - 9/8/2002 7:47:37 PM   
downunder-RCU



Posts: 1125
Joined: 12/27/2001
From: Adelaide, South Australia
Status: offline 		One thing I've found is that if you cool a sample of fuel in the fridge then the oil will seperate out if there's water in the fuel. Shake it while it's still cold and it'll go a muddy brown. As it warms up the muddiness will suddenly disappear and it'll be clear again. The temperature that the oil begins to settle out depends entirely on the % of water in the fuel.

(in reply to jdan)
       Post #: 2

Moisture in fuel ?? - 9/8/2002 10:36:43 PM   
jdan


 

Posts: 91
Joined: 12/17/2001
From: media, PA, USA
Status: offline 		Thanks, downunder. I gave it a try. That's not my problem. I guess I'll have to locate some different fuel.

(in reply to jdan)
       Post #: 3

Moisture in fuel ?? - 9/10/2002 1:25:59 AM   
Sport_Pilot



Posts: 7597
Joined: 1/21/2002
From: Acworth, GA, USA
Status: offline 		This is a new one to me. Seems to me synthetic oil won't separate out. Castor oil may, but I think it depends on the quality of oil. Castor oil is after all vegetable oil and is not manufactured or refined. I know for a fact that low grade castor oil will not mix well and will separate if cooled.

(in reply to jdan)
       Post #: 4

Moisture in fuel ?? - 9/10/2002 7:31:27 AM   
downunder-RCU



Posts: 1125
Joined: 12/27/2001
From: Adelaide, South Australia
Status: offline 		Well these are the figures I found using 18% Mobil Jet Oil 2 for varying water content.

.25% -10C (14F)
.5% -5C (23F)
.75% 0C (32F)
1.0% 5C (41F)
1.25% 11C (52F)
1.5% 16C (61F)
1.75% 22C (72F)
2% 29C (84F)
2.25% 34C (93F)
2.5% 39C (102F)

As you can see there's almost a direct straight line correlation between water % and the temperature. I didn't test an all castor mix as thoroughly as this (for some reason) but out at the flying field I'd been gradually adding water to the fuel and flying. With 80/20 castor fuel the engine ran as normal even with 3% water and was still clear. At 4% I couldn't even get it to fire let alone run! But seeing the ambient temp was around 20C it would appear that a castor based fuel is more tolerant of water than synthetics.

I think I need to do some more tests

(in reply to jdan)
       Post #: 5

Moisture in fuel ?? - 9/10/2002 7:50:02 AM   
Sport_Pilot



Posts: 7597
Joined: 1/21/2002
From: Acworth, GA, USA
Status: offline 		Are you sure the engine is going rich? I don't think I have experianced an engine going rich to cause the plug to go bad. If you are running high nitro and the plug is to hot for the nitro, the plug could become thin causing it to run cool making the engine to seemingly run rich. Try a colder plug and readjust the engine. Actually this could happen with low nitro fuel also, especially with a high compression engine made for low nitro.

Sorry downunder, I didn't understand the question, with water present this makes sence.

(in reply to jdan)
       Post #: 6

Moisture in fuel ?? - 9/10/2002 5:03:30 PM   
jdan


 

Posts: 91
Joined: 12/17/2001
From: media, PA, USA
Status: offline 		I'm using a standard Sonictronics Idle bar plugs, Mach 7, 15%
nitro fuel. Engines affected OS 46 SF and TT46

(in reply to jdan)
       Post #: 7

Moisture in fuel ?? - 10/25/2002 7:16:22 PM   
bdtsr


 

Posts: 1447
Joined: 9/3/2002
From: Egg Harbor Twp., NJ, USA
Status: offline 		Sounds like the engine is being run on the lean side. Try an OS#8 plug (non-idle bar) and peak the engine to max rpm then richen it up for a 300-400rpm drop. If an engine is run lean it will most likely ruin the plug causing a rich running symptom. Also check your fule line and clunk for possible air leaks. This will also cause lean running.

(in reply to jdan)
       Post #: 8

recommendation - 10/28/2002 9:07:52 PM   
Fuel Dinosaur


 

Posts: 85
Joined: 6/25/2002
From: Warrenton, GA, USA
Status: offline 		[QUOTE]Originally posted by downunder
One thing I've found is that if you cool a sample of fuel in the fridge then the oil will seperate out if there's water in the fuel. Shake it while it's still cold and it'll go a muddy brown. As it warms up the muddiness will suddenly disappear and it'll be clear again. The temperature that the oil begins to settle out depends entirely on the % of water in the fuel. [/QUOTE]

I would not recommend EVER putting model airplane fuels in a refrigerator. There is danger of fire and explosion. This is NOT a good idea folks, please. If possible, please store your fuel at room temperature, tightly capped in the dark and if you do, you should not have problems with water in the fuel. When you leave a cap on long term storage loose, you will get some moisture in your fuel. Model fuel methanol soaks up water vapor like a sponge. Sorry to preach a bit, but when you get your butt blown off, it kind of spoils the rest of the flying weekend.

(in reply to jdan)
       Post #: 9

Moisture in fuel ?? - 10/29/2002 5:24:54 AM   
downunder-RCU



Posts: 1125
Joined: 12/27/2001
From: Adelaide, South Australia
Status: offline 		FD.....I fully agree that fuel should not normally go in the fridge, especially diesel fuel with its ether! However in my case I had about 50cc of fuel in a plastic syringe while I was doing those tests (and you should see the freezer compartment after a 2 litre plastic bottle of soft drink exploded ).

(in reply to jdan)
       Post #: 10

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