I really, really want an explanation for this. I filled up the LaSalle last night, nothing exorbitant, not to the brim. Added a few ounces of Marvel Mystery Oil to it, as I usually do. Was working with the carb today to get a leaner mix, just turning the dial on the Carter to see how it worked and whatnot. The car was not running. I noticed a puddle under the rear tire, thought it was odd, smelled it, it's gasoline! Gas tank is not leaking. It ran out of the fill port and right down the side rear panel. Stripped the paint off. I'm furious. There is absolutely nothing I can do about the lost paint.
It did get a bit warmer...so did the sun do this (for which I can only grumble and curse fate) or did messing with the carb somehow push air into the fuel lines and pushed the gas out? Or does the Marvel oil make fuel expand? In short, did I do this by fiddling or just by filling the tank a bit overfull for a warm day?
Me thinks you will have to chastise yourself severely for "over-filling" the fuel tank.
It could be that when you filled the tank, the car was on one slight angle, away from the filler pipe, and when you parked it at home to perform the tuning operation, the car was sitting on an opposing angle, hence the spilling.
Plus, if the exhaust pipe runs close to the tank as it exits the car, this in itself could have resulted in a bit of heat transfer to the fuel inside.
Forther, the fuel coming out of the ground is a lot cooler than the ambient temperature, and then having it sit within the tank, it will reach an ambient temperature, and as a result, expand.
Bruce. >:D
Yeah. It's my fault. Real shame, too.
On a brighter note, I did get the carb working nicely. I was even able to put the oil breather on again.
The same exact thing happened to me some years ago. I had filled the Caddie to the brim to get it ready for a tour the following day. I intended to do more with the car and left it out in the sun while I went in for lunch and when I came back out gas had forced its way back through the vent on the cap and down the side of the fender. At first I was most worried about the asphalt under the car being softened, then I noticed that the paint had gone. This new "gasahol" had attacked the lacquer and it never came back. Turtle Wax Cleaner Wax helped somewhat but only a repaint will fix it.
Vintage Paul
Fuel does not expand
It's the air pocket trapped at one side of the tank which pushes fuel out once the car is parked with inlet at the low side and tank is full enough, and temperature rises after having parked.
Had this happening on my lasalle many times but the paint is fine as there is no ethanol where I live.
Park with inlet at the high side or with tank half full
Liquids (including fuels) most certainly DO expand when heated (or contract when cooled).
Go to this link and scroll down to "How much does gasoline expand with temperature" and click on the right arrow.
http://wiki.answers.com/Q/How_much_does_gasoline_expand_with_temperature?#slide=2
That is why there are coolant overflow tanks for the radiator in your car.
That is why a liquid thermometer works.
That is why large aircraft engines such as radials that hold several gallons of oil in a separate tank (rather than a few quarts in your car) that the oil is checked hot and then filled. If filled cold the oil will overflow as it expands with heat --- makes an awful mess.
Water is a little different but it expands and contracts with heating and cooling in its liquid state.
http://www.ehow.com/how-does_5185456_water-expand-contract-heated_.html
From your link:
"Because gasoline expands and contracts based on temperature, the industry uses a standard temperature -- 60 degrees Fahrenheit -- as part of its definition of a gallon. To the industry, a gallon of gasoline is the amount of fuel that occupies 231 cubic inches at 60 degrees.
But at 75 degrees, the same amount of fuel occupies 233.4 cubic inches. At 90 degrees, the gas expands to 235.8 cubic inches. "
So we have a 2% liquid gasoline expansion from 60F to 90F which would be an extreme cold/hot jump in one day, far wider than what the original poster mentionned about his day as he said that it only got "a bit warmer"
If you were to fill the tank up to the fuel cap level, amounting to 20 GAL or so, a 30F temperature jump will increase liquid gasoline by 0.4 gal, which could only overflow PROVIDED you drove less than a 4.5 Miles distance back to your house, burning that 0.4 GAL away.
But yes liquid expands so your are correct, and even the steel in your gas tank expands However, we don't heat fuel tanks to the same extent that combustion engines or radiator are - where a 180 F jump in 20 minutes is common and would requires a liquid overflow system.
The air pocket created at one side of the fuel tank, filled with expanding gasoline gases and air is enough to continousely push a large amount of liquid gasoline out the the tank on the other side, even when the tank wasn't nearly filled to the max.
Happened to me many times and it took me some time to figure this out..
And as Bruce pointed out, "the fuel coming out of the ground is {could be} a lot cooler than the ambient temperature" --- and thus the temperature difference might well be more than 30 degrees. Trapped air/vapors (if any) would, of course, just add to the problem.
The fuel could be indeeed colder in the ground but its not going to take more than 30 min to get back to ambiant temp once inside the vehicle fuel tank - the overflow did not happen at that moment based on the description.
The overflow happened after the car was parked in the garage - most likely the next morning once the sun got up and temperature started rising inside the tank.
If you half-fill a jerry can with gasoline, and temperature rises, you can feel the gas pressure buildup inside the can. Its the power of these gases which pushes the liquid out.
These fuel tanks were designed at a time when gasoline was heavier thus the gasses were less likely to come into play, today's fuel mix is far more volatile.
As a precaution to avoid a gasoline fire, I jack up the inlet side of the car if it was filled up recently
Caveat: I did say "a bit warmer." Lived in Georgia too long now. A 30-40 degree jump from day to the next is quite normal at this time of year. For the Army (and thus for me) this jump is calculated by "wear field jacket or not." If not, it's a bit warmer than yesterday.
However, the accident exposed the fact that the paint I currently have was pretty poorly applied. I think it was slapped on in a rush for the movie it was in. Luckily any rust there was (if any at all, I think this was stored for a long time before I got it) was stripped before the paint was applied, but the coat is very thin, with perhaps a single layer of clear overtop. I need to repaint eventually anyway. This will just make me do that sooner, since my pride is injured.