How much evaporation from gas tank is normal?

[bikemaniac]

Hi,
My model A has been resting in my uninsulated garage during the later part of the summer. Temperatures reached 80 degrees on some days inside. The tank was filled approx. oke quarter with a closed lid. I always noticed the gasoline smell when I went into the garage. Now, this afternoon I checked the tank and it was bone dry. Is it normal that so much gas can evaporate by itself?
Lucas

[C26Pinelake]

it is my opinion it is not normal and you likely have a leak problem and not an evaporation problem. Start at the obvious problem areas and go from there. I would check the tank first and then the shut off valve or ice versa. Let us know. Wayne

[hardtimes]

Originally Posted by bikemaniac

Hi,
My model A has been resting in my uninsulated garage during the later part of the summer. Temperatures reached 80 degrees on some days inside. The tank was filled approx. oke quarter with a closed lid. I always noticed the gasoline smell when I went into the garage. Now, this afternoon I checked the tank and it was bone dry. Is it normal that so much gas can evaporate by itself?
Lucas

'is it normal' ? NO !

BTW...should have advised that any gas leak is bad, BUT there is a silver lining to be seen here...if the leak is not a crack in the tank ! Take this as a good time to clean 'empty' tank, if indicated as necessary. Take the few connections/lines off and ensure that the 'in tank' pencil pre filter is there or put one in. Make all connections leak proof and be happy that you do not have to DRAIN the tank at this time to accomplish all this ! Good luck

[29er]

Uh, like Wayne sez: not normal to smell what little gas might evaporate from the tank.

Leaks can sometimes be pretty subtle and hard to detect.

Check shut-off valve inside cabin, sediment bowl, fuel line connections at sediment bowl and carb. If you let the gas run out of the carb by allowing the engine to run after you've turned off the shut-off valve, you should have no leaks between there and the carb unless that valve is not working properly.

Look for signs of a leaky valve: is it wet with gas? Are there stains on the floor?

The sediment bowl may leak due to a faulty gasket or crack in the bowl itself. Check the fuel line at the junction with the sediment bowl and where the line connects with the carb.

If you have engine pans, check the one under the carb for signs of dripping. Or check the garage floor under the carb. Mop the bottom of the carb with a paper towel. If it's wet, track down the source. If the leak is coming from the throat of the carb, it may be the float valve is not working or is not adjusted correctly, or the float is "water-logged". Check the fuel line connection where it enters the carb.

[Mike V. Florida]

Originally Posted by C26Pinelake

it is my opinion it is not normal and you likely have a leak problem and not an evaporation problem. Start at the obvious problem areas and go from there. I would check the tank first and then the shut off valve or ice versa. Let us know. Wayne

Originally Posted by hardtimes

'is it normal' ? NO !

Add me to the no way, you have a leak list.

Let's have some fun,

approx 15,140 drips to a gallon (found this on line)
approx 2.5 gal to a quarter tank
37,850 drips to empty the tank
two months storage?
1440 hours
a drip every 2 minutes = 43,200 drips

So with a leak of a drip every 2+ minutes your tank will be empty in two months.

[C26Pinelake]

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Okay Mike gets the Nobel prize for mathematics ! You can't argue with facts. So put some gas in it, run it for a while shut it off as normal, check the likely trouble spots and report back in two weeks ! Wayne

[SAJ]

Originally Posted by Mike V. Florida

Add me to the no way, you have a leak list.

Let's have some fun,

approx 15,140 drips to a gallon (found this on line)
approx 2.5 gal to a quarter tank
37,850 drips to empty the tank
two months storage?
1440 hours
a drip every 2 minutes = 43,200 drips

So with a leak of a drip every 2+ minutes your tank will be empty in two months.

[B]Wow Mike V! For even more fun I reckon your drips are too huge. A US gallon is 3785 CC. So 15140 drips per gallon makes each drip 0.25 cc.
As a qualified drip(per) I know water is about 0.05 cc per drop, and thinner liquids like petrol a bit less. So 2.5 gallons is about 189250 drips - give or take a few each way!
Over 1440 hours to empty, this is 1 drip every 27 seconds. Still very feasible but a rather bigger fire hazard.
Any other takers to dispute my expertise in dripping?
Seriously, in my laboratory work, we often use drops to administer small quantities of liquids too small to weigh accurately. First we count how many drops in, say, 1 gram and proceed to add drips from there. I maintain a drip and a drop are the same size.
Others may disagree. Or maybe my arithmetic is wrong?
SAJ in NZ
EDIT
This just goes to show, people will argue about anything

[billwill]

You have Serious Leak Good Luck

[bikemaniac]

Thanks for all your answers.

Lucas

[Synchro909]

Have you checked around the bracket under the fuel tank that holds the steering column? This is a frequent offender. I think the next most likely culprit is a leaky shut off valve.

[Mike V. Florida]

Originally Posted by SAJ

[B]Wow Mike V! For even more fun I reckon your drips are too huge. A US gallon is 3785 CC. So 15140 drips per gallon makes each drip 0.25 cc.
As a qualified drip(per) I know water is about 0.05 cc per drop, and thinner liquids like petrol a bit less. So 2.5 gallons is about 189250 drips - give or take a few each way!
Over 1440 hours to empty, this is 1 drip every 27 seconds. Still very feasible but a rather bigger fire hazard.
Any other takers to dispute my expertise in dripping?
Seriously, in my laboratory work, we often use drops to administer small quantities of liquids too small to weigh accurately. First we count how many drops in, say, 1 gram and proceed to add drips from there. I maintain a drip and a drop are the same size.
Others may disagree. Or maybe my arithmetic is wrong?
SAJ in NZ
EDIT
This just goes to show, people will argue about anything

I just googled faucet drips and that number came up as the first item (http://water.usgs.gov/edu/sc4.html). A further search just now came up with other numbers. I was just having fun and did not mean for it to be anything else.

[MikeK]

The size (mass) of a liquid drop is dependent on several factors:

1) The surface tension of the liquid. Water and gasoline are not equal!
2) The length (circumference) of the boundary between the hanging drop and the adhesion surface from which it hangs. Small tubes of varying diameters ("droppers") and planar surfaces will all produce different boundary lengths.
3) The adhesion constant between the liquid and substrate from which it hangs. Is the surface philic or phobic?
4) The angle of contact between the drop pendulum and the substrate. Is the drop hanging from a horizontal plane of contact or is the substrate at an angle?

Taking the above all together the mass of the drop will equal the boundary length times the liquid surface tension constant times the sine of the droplet pendulum angle divided by the acceleration constant where the drop hangs (gravity = 9.8 M/sec-sec).

In summary, I have no clue how big the drops are, nor does anyone else. Just fix the leak.

[1crosscut]

You guys got it all wrong!

The neighbor kid snuck in and siphoned the tank dry to fill up his Rat Rod.

[C26Pinelake]

Originally Posted by Mike V. Florida

I just googled faucet drips and that number came up as the first item (http://water.usgs.gov/edu/sc4.html). A further search just now came up with other numbers. I was just having fun and did not mean for it to be anything else.

Mike. The ones that matter understand you were having fun and we thought it was funny. Model A Fords are not scientific . Good work Mike.
Wayne

[SAJ]

Cripes! What did I get myself into? My post was meant as a joke too.Just like Mike K's scientific spoof that followed it.
The important thing is to fix a possibly bad leak or catch 1 Croscutt's siphoner.
SAJ in NZ

[Girl with wrench]

Gas gauge is a possible culprit. Replace the gaskets. That fix solved my 'evaporation' problem.

[C26Pinelake]

Originally Posted by Girl with wrench

Gas gauge is a possible culprit. Replace the gaskets. That fix solved my 'evaporation' problem.

Was your first clue a wet shoe ( lol ) ?
Wayne

[Girl with wrench]

Nope. The gas was leaking down behind the instrument panel, but so slowly that there was never enough to drip on the floor - or my shoes.

Girl with dry toes.

[Mitch//pa]

Originally Posted by Girl with wrench

Nope. The gas was leaking down behind the instrument panel, but so slowly that there was never enough to drip on the floor - or my shoes.

Girl with dry toes.

you should have been able to smell the fumes in the cabin from the gauge leak..

Girl with sensitive nose

[C26Pinelake]

Originally Posted by Mitch//pa

you should have been able to smell the fumes in the cabin from the gauge leak..

Girl with sensitive nose

Good line for sure ! Only the nose knows !
Wayne