How to Check and Add Radiator Fluid


Your vehicle’s radiator is responsible for keeping your engine cool and running smoothly. The radiator fluid, also known as antifreeze, needs to be checked and refilled from time to time. Fortunately, checking and adding radiator fluid is a breeze. If your vehicle has an overflow tank or reservoir, check the side of the tank to see if the fluid reaches the fill line. If the level is low, pour the antifreeze directly into the tank, not the radiator. If your vehicle doesn't have an overflow tank, remove the radiator cap and check the fluid levels to see if you need to add any antifreeze. If you do, pour the fluid in small amounts until it reaches the fill line marked inside of the radiator. It’s also a good idea to check the condition of the fluid and test it with a testing kit to make sure it’s performing optimally.

Part 1
Inspecting the Fluid Level

Inspecting the Fluid Level on How to Check and Add Radiator Fluid

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In order to check the fluid level in your radiator, the vehicle needs to be level so the fluid line isn’t slanted or uneven. Find an area with level ground and open the hood of the vehicle.[1] If the vehicle is parked at an angle, it may be more difficult to reach the radiator cap. Make sure the hood is propped open securely so it doesn’t fall on you while you’re checking the fluid levels.

Inspecting the Fluid Level on How to Check and Add Radiator Fluid

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When your vehicle’s engine is hot, the radiator is hot and can release steam, which can burn you if you’re exposed to it. Before you begin checking your radiator fluid levels, you need to make sure the engine isn’t running and wait until it’s cool enough to touch.[2]If you’ve been driving for a few hours, wait at least 1 hour for your engine to cool down.

Inspecting the Fluid Level on How to Check and Add Radiator Fluid

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Most modern vehicles have an overflow tank or a fluid reservoir that holds the radiator fluid. Look for a clear or see-through plastic container connected to the radiator by a tube. Check the side of the tank to see if the fluid level reaches the fill line.[3]The tank may have a line that says “Full” or it may just have a raised line demarcating the maximum fluid level.

Inspecting the Fluid Level on How to Check and Add Radiator Fluid

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In most vehicles, the radiator is located in the front of the engine and has a small cap with 2 little rounded edges on the side. To remove the cap, press down on it and twist counterclockwise to release the locking mechanism and pull the cap off.[4] Then, check to make sure the fluid reaches the "fill" line.[5] If your radiator doesn’t have a fill line, but you can see the fluid full to the top of the radiator, then you don’t need to add any fluid.Emergency Tip: Use a towel or arag to cover the radiator cap ifyou can’t wait for the engineto cool down before you check oradd fluid to the radiator.Emergency Tip: Use a towel or a rag tocover the radiator cap if you can’twait for the engine to cool downbefore you check or add fluid to theradiator.Emergency Tip: Use a towel or a rag to coverthe radiator cap if you can’t wait for theengine to cool down before you check or addfluid to the radiator.Emergency Tip: Use a towel or a rag to cover the radiator cap if youcan’t wait for the engine to cool down before you check or add fluidto the radiator.Emergency Tip: Use a towel or a rag to cover the radiator cap if you can’twait for the engine to cool down before you check or add fluid to theradiator.

Part 2
Adding Antifreeze

Adding Antifreeze on How to Check and Add Radiator Fluid

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Your vehicle may require a specific type of fluid for the radiator. Take a look through your vehicle’s manual to see what type of antifreeze you need to add. Alternatively, search for the specific type of antifreeze that you need for your vehicle online.[6] Some antifreeze will have directions to mix and dilute the fluid with 50% distilled water. Follow the directions carefully. IAT formula antifreeze is green in color and is the most common type of fluid used in vehicles. Many GM vehicles use an orange antifreeze known as Dex-Cool. If you have an older vehicle, you may need a formula with a special additive to allow the antifreeze to work effectively in your vehicle.

Adding Antifreeze on How to Check and Add Radiator Fluid

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If your vehicle has a radiator fluid reservoir or overflow tank, do not add fluid directly to the radiator. Instead, remove the plastic cap from the top of the tank and pour the antifreeze into it until it reaches the fill line marked on the side.[7]

Adding Antifreeze on How to Check and Add Radiator Fluid

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To prevent spilling any of the fluid when you add it, place a funnel inside of the opening of the radiator.[8] Start adding the fluid in small amounts. Don’t pour all of the antifreeze at once or it could spill out of the radiator. Allow the fluid to bubble and settle in the radiator, then check the level. Continue slowly adding fluid until it reaches the fill line.[9] Make sure the funnel is clean so you don’t get any dirt or debris in the radiator. Spilling antifreeze on your engine could cause it to stain your engine or produce smoke when the engine heats up. Warning: Fill the radiator itselfonly if your vehicle doesn’thave an overflow reservoir!Warning: Fill the radiator itself onlyif your vehicle doesn’t have anoverflow reservoir!Warning: Fill the radiator itself only ifyour vehicle doesn’t have an overflowreservoir!Warning: Fill the radiator itself only if your vehicle doesn’t have anoverflow reservoir!Warning: Fill the radiator itself only if your vehicle doesn’t have anoverflow reservoir!

Adding Antifreeze on How to Check and Add Radiator Fluid

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After you’ve added enough fluid to reach the fill line on either the overflow tank or radiator, replace the cap to prevent any of it from spilling out when the vehicle is in motion. Turn the cap clockwise until it clicks into place.[10]

Part 3
Testing the Antifreeze

Testing the Antifreeze on How to Check and Add Radiator Fluid

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The antifreeze should be slightly transparent and should be the original color of the fluid when you added it to the radiator. Milky or cloudy fluid is a sign that the fluid has been contaminated with oil, which indicates a serious problem with your engine. Release the plug on the bottom of the radiator to drain the fluid, then replace the plug and refill the radiator with fluid.[11] Bring the vehicle to a mechanic to inspect your vehicle immediately to prevent further damage. Check the fluid in the overflow tank or reservoir as well.Tip: Use a flashlight to lookdown into the fluid to inspectits color and appearance.Tip: Use a flashlight to look downinto the fluid to inspect its colorand appearance.Tip: Use a flashlight to look down into thefluid to inspect its color and appearance.Tip: Use a flashlight to look down into the fluid to inspect its colorand appearance.Tip: Use a flashlight to look down into the fluid to inspect its color andappearance.

Testing the Antifreeze on How to Check and Add Radiator Fluid

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If you see small particles or dirt in the antifreeze, it’s a definite sign of contamination. Bring the vehicle to a certified mechanic who can check the rest of your radiator and engine to identify the source of the contamination.[12] Do not drive the vehicle except to deliver it to a mechanic. Particles and contamination could damage the engine and require costly repairs. Inspect the fluid in the overflow tank for any debris or particles.

Testing the Antifreeze on How to Check and Add Radiator Fluid

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Over time, antifreeze can lose effectiveness and may need to be replaced. But before you do that, you can test it to see how well it’s performing. Take off the radiator cap and insert an antifreeze test strip until it contacts the fluid inside of the radiator. The test strip will change color once it absorbs the antifreeze. Check the testing kit to see what the color indicates and what action you should take.[13] You can find radiator fluid testing kits at auto supply stores and online. Hold the test strip in the antifreeze for at least 3 seconds.