How Do You Check Antifreeze/Coolant Level?

As a driver, knowing how to check the level of antifreeze in your vehicle can help prevent costly damage to your vehicle's engine. Fortunately, this important task can be done quickly and easily, even if you have no experience as a mechanic. We've researched the necessary steps for an antifreeze check, so you'll know what to do for your car.

To check the antifreeze/coolant level in your car: 

  1. Park the car on a level surface, if possible. 
  2. Allow the engine to cool (at rest for 30-mins or more).
  3. Pop the hood. 
  4. Locate the antifreeze/coolant reservoir - a translucent, plastic container at the front of the vehicle near the radiator.
  5. View the antifreeze/coolant level; determine whether coolant is full, med, or low by using the demarcation lines on the reservoir. 

A vehicle's engine coolant is a critical component to keeping your vehicle's engine running smoothly. Allowing the engine to run without it can lead to costly repairs, which can be avoided with basic maintenance. Even if this is your first time under the hood of your car, rest assured that this post will leave you with a rudimentary understanding of not only how to check your coolant levels but why it's so important to do so routinely.

A mechanic pouring antifreeze or coolant to the engine, How Do You Check Antifreeze/Coolant Level?

How To Check The Level Of Antifreeze/Coolant In Your Car

A mechanic pouring coolant on the engine of a car

Radiator coolant, more commonly known as antifreeze, has a dual purpose for a vehicle's engine. While water alone can cool your engine, antifreeze acts as an agent that chemically raises the boiling point of the water that it's mixed with. This pushes heat away from the engine and allows your vehicle to operate without interruption due to engine heat. As its name suggests, antifreeze keeps the water inside your engine from freezing during the winter by also lowering the freezing point, making it more effective than water alone during the coldest months. 

Locate the Antifreeze/Coolant Reservoir and Check the Level of Fluid

Your car's antifreeze level can be checked by locating the coolant reservoir and seeing what level the coolant is sitting at. While your car's engine is cold (meaning it's not been running for at least thirty minutes), pop your hood and locate the radiator near the front of your vehicle.  The coolant reservoir is a translucent plastic container near the radiator, with level markings along one side of it. You'll be able to see the level of coolant using the markings on the reservoir. Of course, you will want to make certain that the vehicle is parked as close to level as possible so that the coolant fluid shows level in the reservoir. 

Add Antifreeze/Coolant - If Necessary

Before adding any coolant to your vehicle, consult your owner's manual to see if a factory recommended type of coolant is recommended. It's also important to know if you're adding concentrated coolant or a premade mixture of antifreeze and water. If it's a concentrated coolant, you'll need to mix it with water at a 1:1 ratio. If it's premixed, you'll need to do nothing more than add the coolant to the reservoir.

When the coolant reservoir is low but still holds coolant, it will be safe to pour coolant into it.  However, if the reservoir is dry, it's important that the engine has been off for at least thirty minutes and is cool to the touch. Adding cold liquid directly into the radiator, either by having it rush through from an empty reservoir or by pouring it directly into the radiator itself, can damage the radiator. For additional information, consult your vehicle's owner's manual.

Use Caution When Handling Antifreeze/Coolant

When adding radiator coolant to your vehicle's reservoir, certain precautions should be taken to avoid risks to your health and damage to your vehicle:

  • Radiator coolant is not a caustic chemical (meaning it isn't corrosive and won't burn your skin), but you should take care not to get any on yourself. If you accidentally slosh a bit on your hands or arms, washing it off with soap and warm water as soon as possible is advised.
  • Any antifreeze spilled onto the ground should be mopped up as soon as possible to avoid health risks to animals. Antifreeze has a sweet taste to it, and dogs and cats are known to be attracted to the taste. As good as this fluid is for your vehicle, it is poisonous to animals and humans, so please pour carefully and clean up thoroughly.
  • Please remember that engines can be VERY hot. Make absolutely certain that you're not touching any parts under the hood until the vehicle has had time to cool off after running. Should you be forced to work under the hood of your vehicle while the car is still running or hot, take every precaution necessary to avoid burns from hot metal or scalding hot fluids.

For more safe handing tips, check out "Is Engine Coolant Flammable? [Including Safe Handling Tips]."

Keep Antifreeze/Coolant Handy

It's recommended that you carry a container of engine coolant in your vehicle in case your reservoir or radiator runs low while you're on the road. Imagine the frustration of being stranded at the side of the highway when all you'd need to get back into gear is a half-gallon container of liquid! This is especially important for older vehicles and ones that have never had their radiators flushed and original coolant replaced.

How Do I Know if My Coolant is Low?

The worst way to find out if your coolant is low is if your car suddenly overheats, causing your car's engine to shut off while steam pours out from under your hood. In order to avoid this scenario, check your coolant levels every two weeks. Your vehicle's coolant reservoir will indicate how much coolant needs to be added. Pay attention to the fill marks on the side of the plastic reservoir. If the fluid level is anywhere below the "full" mark at the top, then your coolant is technically low.

For more information, check out "Driving With Low Engine Coolant - Is It Safe?"

Why is My Coolant Reservoir Empty?

There are several reasons why your coolant reservoir is empty, but it is relatively easy to determine the cause. A common reason is not having the coolant reservoir cap on the reservoir correctly. If this cap is loose or missing altogether, the coolant will slosh out while the car is in motion or will evaporate from the reservoir. This is also true of the radiator cap. Check to make sure that the radiator cap is securely fastened.

In addition to a loose radiator cap being the culprit, a faulty radiator cap that no longer can hold pressure inside the radiator could be the problem. If the engine has ever overheated, there's a possibility that damage was done to the cap or its seals. This cap can be easily replaced at a local auto parts store.

Cracks or holes in the reservoir itself will cause coolant to leak out or evaporate. After checking your reservoir and radiator caps, closely inspect the reservoir to see if it's been damaged in any way. Some minor cracks may be more difficult to detect with the naked eye, but you will be able to notice any leakage from the reservoir after filling if you place a dry, white paper towel around it. If there's any moisture on the towel that matches the color of the radiator coolant, then you've found the cause.

If the above steps are taken, and the coolant reservoir continues to run out quickly, then the issue may be a hole or crack in the radiator itself. Replacing the radiator will be more labor-intensive than replacing caps or reservoirs but can be done by most shadetree mechanics.

What is the Correct Level of Engine Coolant?

When checking the reservoir's coolant level, you'll notice gradient fill marks along one side of the reservoir. The top one will read "full." Pouring engine coolant into the reservoir until the coolant meets this level is correct.

A car owner checking the coolant level of a car

Is it Normal for Coolant to Get Low?

As a car ages, it is normal to see the original coolant level drop. Even with caps firmly in place and no holes or cracks in the reservoir or radiator, evaporation will happen naturally over time. The older the coolant gets, the more impurities will be absorbed, leading to the coolant gradually evaporating faster. Part of routine maintenance is to totally replace the coolant over time. Consult with a local mechanic for how often this should be done, or read your owner's manual for manufacturer's recommendations on a total radiator flush and coolant replacement. 

Can I Refill Coolant Myself?

If you can pop the hood of your vehicle and unscrew the coolant reservoir cap, you can easily refill the engine coolant yourself. Just be sure to have a rag handy to wipe up any excess coolant that you might have spilled.

A man pouring coolant on the engine

In Conclusion

Routine vehicle maintenance is critical to prolonging the life of your car or truck and the safety of you and your passengers. Follow the recommendations found in your owner's manual for the types and frequencies of maintenances that need to be performed. Don't hesitate to find a trusted mechanic to accomplish any of the maintenance that you're not comfortable taking care of yourself.

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