Does gas evaporate without a gas cap?

There are issues every vehicle owner must experience. There are no free parking spots – check! There’s no space inside your trunk for your shopping bags – check! There’s no gas cap at… Hold on a second, w-w-what?

Yup, it’s something that can happen. The thing is: you’d never notice there’s a gas cap missing from your vehicle. That is, until the next time you stop for gasoline at a petrol station. There’s a good chance some folks easily go on without it. But wouldn’t the gas in your tank evaporate without a gas cap?

Gasoline will evaporate if you’re driving a gas cap, but not entirely. Not even close; it will just slightly reduce your fuel’s efficiency. Still, you should avoid driving without a gas cap. As soon as you notice it’s not there or it’s damaged – replace it! 

If you’re wondering whether there’s more to this than the sentences above… Needless to say, keep on reading!

What’s a gas cap?

We reckon you already know this. Still, it’s best if we explain the terms we’ll be using a lot today. A gas cap is that little physical seal that keeps the gasoline in your car’s tank fresh. It’s the little piece you take each time you sip gas. It helps your car by:

  • improving safety en général.
  • increasing fuel economy.
  • reducing emissions.
  • keeping dirt and other contaminants out of your gas tank.

It’s one of the most important pieces your car consists of. Unfortunately, folks tend to diminish its significance. Once you see how volatile gasoline is, you’ll feel more grateful to your gas cap. It’s about time someone settles the score once and for all!

Wait, does gas evaporate?

That’s right – gas has that little special trait. You’ll want to know that gasoline is highly volatile. That means that it evaporates pretty fast.

Gasoline releases fumes at the temperature of -40°F (-40°C). That’s right, there’s where the two scales meet to become one. Anyway, you’ll also want to know that gasoline fumes art highly toxic, not to mention – flammable. As if we didn’t mention that quite a lot on this blog, right? Our informal motto is better safe than sorry.

How fast the gasoline will evaporate depends on the amount of it. Also, you’ll need to consider the surface it’s spilled onto. For instance, it will evaporate faster if you spill it over the concrete rather than soil. Soil is permeable and it basically soaks in the gasoline.

Depending on how much gasoline is spilled, the whole process can take from days to years, even – decades. For more interesting info about that topic, follow this link.

How fast does gasoline evaporate?

As we already said, it all depends on how much you’ve spilled. Also, one needs to think about where the spill is. In other words: what is the surface onto which the gasoline landed?

Here’s a simple explanation! The more permeable a surface, the more time it will need for gasoline to evaporate. The smaller the amount of gasoline spilled – the better the timing of evaporation. Of course, if you don’t clean it up properly, you can’t count on the timing we’ve mentioned.

There’s a lot more from where the above info came from. If you’re wondering where’s that place, click right here for an expert answer.

How long does gas take to evaporate on a concrete?

Okay, so we’re talking about a non-permeable surface. If you spill gas on concrete, it will evaporate pretty fast. Some experts say that it takes about an hour and a half for 90% of it to go away. That’s pretty quick, huh?

How long does it take spilled gas to evaporate?

Gasoline spills aren’t something you’d call uncommon. God knows we’ve all been there. Anyway, what happens if you spill some gas onto your clothes. Will it evaporate soon? Here’s a quick step-by-step guide:

  • Step #1: remove the excess gas using thick paper towels.
  • Step #2: pretreat the clothes by soaking them in a premade mix. Use vinegar and hot water combo.
  • Step #3: put the clothes into the machine.
  • Step #4: the odor’s still there after the wash? Soak your clothes in water & baking soda mix.
  • Step #5: dry the clothes out in the open air.

For a more in-depth look at the issue, we recommend you read this one. Let’s begin tackling the main question for today: does gas evaporate without a gas cap?

A woman sipping gas at a gas station.

Does gas evaporate without a gas cap?

The simple answer is: yes, it absolutely does. That’s why there’s a gas cap in your car in the first place. It keeps your gas from exposure to air. In other words: it keeps the whole evaporating-on-the-outside option at bay.

Of course, gasoline produces vapors while inside the trunk. It’s not a mystery at all! Still, it’s the gas cap that keeps all these vapors inside so your vehicle’s engine can put them to good use.

Did you know that a broken/missing fuel cap can reduce the fuel’s efficiency? Now that you do, you’ll pay more attention to the unjustly-ignored item called the gas cap.

How to know if the cap isn’t fitting properly?

That’s a good question! Luckily, we’ve got a solution to the issue. If there’s an issue to be solved, of course.

To figure out if the gas cap is loose or poorly fitting, do the following: conduct a simple listening test. While you’re unscrewing the gas cap, listen carefully. If you hear something resembling a hiss, then… Don’t panic, it’s nothing to worry about! The hiss usually means that the gas cap is a good fit.

What happens if you drive around without a gas cap?

Usually, driving without a gas cap is alright. That is: at least for a while. There are no risks such as gas fumes finding their way into your passenger cabin. Thanks to the flapper valve, gasoline won’t leak either. However, driving long distances without a cap can decrease fuel’s efficiency. Also, it might do some damage to the engine.

All in all: don’t hesitate much and obtain a new one. Simple as that!

How to know if you’re driving without a gas cap?

It’s safe to assume your car has a check engine light, since, well, most cars today do. If you’re driving without a gas cap, you’re bound to notice it soon. You’ll most likely see the light illuminate just a couple of minutes after you’ve sipped some gas. Also, some up-to-date modern cars have an individual gas cap light.

Lastly, don’t worry if either of the mentioned lights stays on after you’ve (re)placed the cap. There’s a chance you’ll have to drive for a while before it goes into normal mode. Your vehicle’s computer will need about 160 km (100 miles) or so to notice everything’s ok now.

Will driving without a fuel cap damage the engine?

As we’ve already said, driving without a gas cap ain’t so dangerous. However, that doesn’t mean you should ignore the issue. Also, some say that a cap-less gas tank isn’t a threat to your engine. How’s that? Well, vehicles usually have a so-called flapper valve that helps against fuel leakage.

All in all: we recommend you replace your gas cap immediately as you notice something’s up. The gas cap acts as something of a shield against mud or dirt particles. They can damage your vehicle’s engine, although not that easy.

If you’re wondering where does one looks for gas caps, click here.

What about replacing your gas cap every once in a while?

You’ve read the last paragraph. It might’ve inspired you to ask: wait, should I replace my gas cap every one in a while? If that’s how it happened, you’ll want to know the following:

  • Gas caps should last for about 50k miles (about 80.5k km) on average. 
  • However, if they’re damaged, they’ll probably need an early replacement.

And how much will that cost me?

Okay, so the average cost of a gas-cap-replacement process is somewhere between $74 and $80. You’ll pay between $17 and $23 for labor, and about $57 for parts.

Lastly, are gas caps universal?

Last but not least, here’s an answer to the issue many folks ask Google about. Here’s a simple answer: most gas caps are, in fact, universal. They can fit into any car or SUV. Most usually, they have a diameter of 55-57 mm or 58-60 mm including the threads.

Does gas evaporate without a gas cap? (a summary)

Okay, so we’re pretty close to finishing today’s talk (if we can call it like that). Anyway, it might be best to do a bit of a check-up concerning the article’s main topic. So, does gas evaporate without a gas cap?

The simplest answer is: yup, it does. Otherwise, there wouldn’t be a gas cap in the first place. Needless to mention, it keeps your gas protected from air exposure. A missing gas cap can slightly reduce your fuel’s efficiency. Even if used the adjective slightly, you should still avoid driving without it.

That’s about it for the whole driving-without-a-gas-cap issue. Hopefully, you’ve enjoyed reading this one. Also, we hope you’ll put this info to some good use!

For more gasoline-related topics, don’t hesitate to visit our blog page.