Does Windshield Washer Fluid Evaporate? (Explained)

Methanol is the main ingredient used to make windshield washer fluids. Certain brands also add ethylene glycol to the mixture as it increases the washer fluid’s ability to clean the windshield.

If you were very keen during science classes, then you may remember that methanol evaporates at room temperature because of its low boiling point.

With the above information in mind. It’s easy to put one and two together. That is, if you have recently noticed that your windshield washer fluid level is dropping at a fast rate, you may be wondering if it evaporates.

Yes, windshield washer fluid will evaporate when exposed to high temperatures. However, it has been formulated to withstand both low and high temperatures in the reservoir.

Plus, if you have a well-sealed reservoir, even if it evaporates, there will be nowhere for it to go.

Evaporation isn’t the reason why the level of washer fluid in your reservoir is dropping faster than it should be. The amount of windshield water fluid that evaporates from a reservoir is too little for you to even notice it.

So, if you are worried about why your windshield washer fluid levels are always dropping, look for other causes.

does windshield washer fluid evaporate

Is My Windshield Washer Evaporating?

If you visit your mechanic and tell them that you think your windshield washer fluid is evaporating, the first thing they will look for is a leak.

The reason for this is that, even though windshield washer fluid is vulnerable to evaporation, the amount that will be lost because of this will be too little for you to even realize.

It does contain methanol which evaporates readily at room temperature. However, the fluid is formulated to remain intact at room temperature.

If this wasn’t the case, how would you even refill your reservoir? Wouldn’t it evaporate as soon as you open a can of washer fluid?

The bottom line is, that windshield washers can evaporate. But it doesn’t do so at a fast rate. The evaporation of windshield washer fluid is so slow that you wouldn’t even notice it as it happens.

And if your car is losing a lot of washer fluid than normal, you are either dealing with a leak or someone is running your sprayers when you are sleeping.

How Can it be a Leak Yet There are No Puddles on My Garage Floor?

If this is the case, then we understand why you may think that your windshield washer fluid is evaporating.

The likes of oil leaks are easily noticeable because they leave puddles in the garage and are easily visible when you look under your car.

However, windshield washer fluid leaks can be difficult to realize because of the following factors.

The first issue is, that modern windshield washer reservoirs come in odd shapes and are placed in compartments that are not easy to see.

For example, when you pop your hood, can you see the entire reservoir? Probably not.

Nowadays, the much you can see is the neck of a windshield washer reservoir and the tank is strategically placed either on top or the side of your front wheel wells.

Because of how hidden this tank is, even if there is a leak, it may not be easily noticeable when you look under the hood or leave the car parked in the garage.

The second reason why windshield washer fluid leaks are hard to notice is that when a car is running when the fluid drips on parts of the engine that are hot, it can easily evaporate therefore not leaving a trace behind.

And, some car owners have reported that most windshield washer fluid leaks happen when the car is running because of the increased pressure in the reservoir.

And to wrap up the issue of there being leaks and no paddle, you should know that most windshield washer fluids, though colored, fade to clear when they drip on concrete. This can even make it more difficult for you to notice a leak.

Are There Other Reasons Why My Windshield Washer Fluid is Disappearing?

It is practically impossible for windshield washer fluid to disappear into thin air. That we have adequately explained in the above sub-topics.

However, other than leaks, there are several other reasons why your windshield washer fluid may be disappearing and not leaving visible leaks. They include;

• A loose lid or cap

Before you look at other culprits, what is the condition of your lid? If it’s loose then that could be the source of your woes.

A loose lid is going to spill windshield washer fluid when you are driving. And if you don’t fix it as soon as possible, you may lose a lot of washer fluid especially when driving on bumpy roads.

• Tubing leak

Though not very common, the tubes that take the washer fluid from the reservoir tank to the nozzles on your windshield can get damaged and leak fluid when you run the sprayers.

If this is the case, you will have to identify where the fluid is leaking from and repair it.

These two causes mostly apply when the windshield washer fluid only disappears when you drive the vehicle. When it stays parked, the fluid level remains intact.

Is the Evaporation Theory Dismissible?

If you read through most car forums, you will realize that there are a good number of people who believe in the evaporation theory.

One of the reasons why you may be losing considerable amounts of windshield washer fluid is due to evaporation.

Those who believe in this theory argue that because windshield washer fluid contains methanol, it evaporates very fast.

And the fact that the reservoir is closely located to the engine which gets hot when driving, there is a high chance that the heat is responsible for accelerating the evaporation.

However, this theory does have its limitations. The first one is, if this were the case all cars would be using up gallons of windshield washer fluid in a matter of days.

Secondly, reservoir tanks aren’t just built from ordinary materials. Manufacturers of cars are aware of how hot the area under the hood can get. That’s why they use high-grade plastic to build the windshield washer reservoir tank.

When it comes to car-related issues, it is essential to base one’s arguments on facts. The theory that windshield washer fluid can evaporate and leave the reservoir tank empty is misleading.

If this is a problem that you have realized, look for reasonable causes so that you can find an appropriate solution.

Can the Reservoir Tank Have Anything to Do with the Disappearance of Windshield Washer Fluid?

Of course, it can. Being the object that stores and holds the windshield washer fluid, it is directly responsible for any disappearances.

Now that we have ruled out the evaporation theory, as a car owner, you should look at other factors such as a damaged windshield washer fluid tank.

And because most tanks in modern cars are not visible because they are hidden by other components, it can be hard to assess if the tank is damaged.

Below, we have compiled some of the common signs of a bad reservoir tank. This will help you determine whether the reservoir tank is the reason why your windshield washer fluid is disappearing. These signs include;

Finding leaks below the car. This, as mentioned earlier is the most common sign of a damaged reservoir tank.

The second sign is the washer fluid not being able to spray onto the windshield. If your tank is damaged, there isn’t going to be any fluid that can be sprayed on the windshield.

Also, if you are always refilling your windshield washer fluid, it’s not evaporating but it may be leaking from the tank.

Finally, if there are cracks in the tank, that’s where the fluid may be leaking from.

If your tank is causing the windshield washer fluid to disappear, you will have to replace it. In most cases, sealants don’t offer lasting results.

The only way to ensure that you don’t keep on refilling the washers is by getting a newer tank with no cracks.

Another thing that you need to know regarding the tank is that if you have a tiny one, and you use the sprayers often, it will drain faster.

Nowadays, it’s very rare for you to find a car with a small windshield washer fluid reservoir tank.

What about the Windshield Washer Fluid Hose?

Other than the tank, the tube carrying the windshield washer fluid to the spray nozzle can also be damaged by wear or heat from the engine. And this could force your fluid system to use up more fluid than needed.

If there is a hole or leak along the tube, when you engage the sprayer, the fluid coming from the nozzles will be little because most of it will exit through the holes in the tube.

Similar to the reservoir tank, the best fix for a leaking washer fluid hose is to replace it. However, with some pliers, you can cut the damaged part and join the tubes using cable ties.

But first, you will have to identify the location of your windshield washer fluid hose. This information should be in your manual.

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