44 years ago I got my driver’s license. Most of the time since has been spent living and driving in the state of Michigan. One piece of advice from my father that I remember to this day (but don’t really follow) is to not let one’s gas level get below a quarter tank or else run the risk of getting gas line freeze.
It’s currently 0 degrees (F) outside (-10 with windchill) and my car is running on fumes. A few minutes ago I went to start it up and…it fired up cold no problem whatsoever. It occurs to me this is hardly the first time that’s happened. In fact, for the past 44 years I have never once gotten gas line freeze. Which raises the question - is gas line freeze a real thing affecting cars nowadays, or was this a bigger problem back in the days of leaded fuel and older cars that ran on ‘premium’ gasoline?
I’ve heard that too, but never had it happen. I’d WAG it happened more commonly when tanks weren’t sealed as well and water got into them. The water will sink to the bottom of the tank and I could see a slug of that freezing somewhere in the system and causing a problem.
I’ve been driving since the mid-80s and live in Southern Ontario. I have had doors freeze shut, windshield wipers frozen to the windshield, and a dead battery from the cold. I have never had a frozen fuel line.
The theory is that as the temperature goes up and down, water condenses out of the air in the gas tank. This is why the less gas you have in your tank (more room for air) the more likely you are to have the problem. Once you get some water in your gas tank and it gets cold enough, the water freezes, a chunk of ice gets into your fuel line, and you’re stuck.
It seems like a reasonable theory, but it’s never happened to me or to anyone that I know personally. Mr. Google didn’t give me any real life examples of it happening in the first few pages of search results either.
The theory is that the more air you have in the tank, the more water can condense out of it.
The fact that water is heavier doesn’t really matter except that it means any water that is in the tank will end up at the bottom, where it can easily get sucked into the fuel pickup.
In other words, it’s not about ice floating in the tank, it’s about more air (less gas) producing enough water to make a big enough ice chunk to block the fuel line.
Water condensing in the fuel tanks of gasoline-powered airplanes is a very real thing.
All fuel tanks / systems are equipped with quick drains at the low point(s) to drain accumulated water. And every GA pilot drains those pretty religiously. There’s a standard clear plastic cup / drain release tool to drain the low point liquid into, then scrutinize it as to all water, all fuel, or some of each.
Finding a teaspoon to 1/4c of water in a 20 gallon tank is not rare at all.
Fellow Michiganian here. One bitter cold day a half dozen years ago I couldn’t start my '05 Honda CRV and called AAA. The fellow that came out made a few failed attempts to get the engine to turn over then he ultimately grabbed a hammer, reached underneath and violently struck something multiple times (I cringed but did not ask what). It worked.
I have had it happen, years ago. We used to buy little vials of gas line anti-freeze to put in the tank when we filled up.
Nowadays, the gas companies have winter blends with gas line anti freeze built in, only sold in winter.
Plus, it’s not necessarily water that is the issue, but the gas itself. Gas doesn’t usually freeze solid, but the concern is that the gas can get slushy at low temps, especially in the fuel line, given its narrow width. The gas doesn’t have to freeze solid to cause a problem; sludgy gas in the fuel line can affect performance.
From a quick Google, here’s an info sheet from Autozone:
ETA: windchill, mentioned in the OP, doesn’t affect inanimate objects like gas. Their temperature will not go below the actual ambient temp. Windchill is meant as a measure of how quickly the human body can lose heat in extreme cold and wind, leading to hypothermia.
So for a car with a 12 gallon tank, let’s suppose it’s got two gallons of fuel and ten gallons of air. That works out to about 0.011 pounds of air. Suppose that air is at 45F, 50% humidity. The water vapor content is 22 grains of water per pound of air.
Now cool that tank down to 20F. at 100% relative humidity, the moisture content is 15 grains/lb, so some of that water vapor has condensed: 7 grains of condensate per pound of air, times 0.011 pounds of air, equals 0.077 grains of water. The density of liquid water is about 253 grains per cubic inch, so now your tank has roughly 0.0003 cubic inches of ice at the bottom of the tank. That’s a cube of water about 1/16" on a side, assuming it all coalesces into a single bolus.
The tank will breathe due to daily temperature cycling, but with not much volume change, since the daily temperature swing won’t be very big; swinging between 20 and 40F each day, it’ll exhale/inhale about a half-gallon of outside air every day. If the ambient humidity of the air is greater than about 34%, then some portion of that humidity will condense inside the tank the next night when the temp gets back down to 20F. But it won’t be much, since you’ve only brought in a half-gallon of humid air instead of the 10 gallons of humid air that the tank started with.
If the diurnal temperature cycle is entirely below freezing, the frost that evolves inside the tank won’t coalesce into a single solid icebergling; you’ll just have something like frazil ice, a gasoline slushee.
Large bits of ice should get caught on the gravel screen at the pump’s inlet; anything small enough to get through is not going to damage or stall the fuel pump, and once it gets to the fuel injectors, it should melt and get squirted into the engine without incident.
If your engine wouldn’t turn over but your battery was OK, then maybe your starter wasn’t kicking its pinion gear out to engage with the flywheel’s ring gear. If it was on a cold winter day, this may have been because the mechanism was iced up, and hammering cracked the ice up enough to allow free movement again.
Here’s what that’s supposed to look like:
If the little pinion gear can’t come out and play with the flywheel’s big ring gear, it can’t turn the engine.
Am I right in guessing that over-wing GA planes don’t use a fuel pump? If so, it’s not hard to imagine ice crystals accumulating in (and eventually blocking) the line from the wing to the carb, since you wouldn’t have a fuel pump chewing up ice and cramming fuel past minor obstructions.
Years ago,I had a problem with gas I frequently bought at one station. Sluggish startup and other signs of water in the gas in cold weather. I stopped going there and no problem since.
I have always assumed that since water and gasoline are immiscible but water and alcohol are soluble that the 10% alcohol gasoline pretty much everyone uses these days substitutes for the bottles of methanol we’d use during the winter back in the old days.
Alaskan who lived in Fairbanks for two years, where it’s common for winter temps to dip to -40F or lower. Gas will gel, oil will freeze at those temps. People on campus who for some reason didn’t have a crankcase heater, would light a small bonfire under their oil pans when it was that cold to try and get some circulation going.
Re the folks mentioning “the lowest point in the gas tank”: Wouldn’t that be where the fuel line leaves the tank? If it’s anywhere else, then you’ve got gas in the tank you can’t use.
