How to Check and Change Your Engine Coolant

What is Coolant? Why is It so Important?

Coolant serves two main purposes:

  1. It transfers heat to keep your engine from overheating.
  2. It keeps your engine from freezing when temperatures drop below freezing.

In other words, coolant helps regulate temperature for your engine, keeping it from getting too hot or too cold so it doesn’t get damaged.

Problems with a car’s cooling system are one of the leading causes of vehicle breakdowns. That’s why it’s so important that you periodically check your engine coolant in the same way that you would periodically check your oil.

When you check your coolant, you’ll want to be sure your coolant is at the proper level and that the quality is still okay, because, just like anything else, coolant doesn’t last forever. The quality degrades over time as it becomes more acidic. Bad coolant can cause corrosion and damage your radiator, water pump and thermostat, which can be costly to repair. Not to mention, bad coolant will stop your radiator from being able to effectively cool your engine, which could cause overheating and severe damage to your engine. No one wants that. Read on to find out the warning signs that could be telling you your coolant needs attention.

Signs Your Coolant Needs Attention

Your vehicle’s coolant light should come on on your dashboard if your coolant gets too low. If this light comes on, you’ll need to add a 50/50 mix of coolant (antifreeze) and distilled water to your radiator. While doing this, you’ll want to check the hoses, belt and radiator to be sure there aren’t any leaks that might be causing the coolant level to be low.

If the temperature gauge on your dashboard is inching closer and closer to the danger zone, that might also indicate that there is an issue with your coolant and it needs to be replaced.

You’ll want to check your coolant periodically to be sure all is well. Coolant is normally light green, yellow or orange. If your coolant is any other color, it is cause for concern. A reddish tint may indicate that rust is present. Rust can clog your system and cause your car to overheat. Black may indicate that oil is leaking into the radiator.

If you notice a sweet smell coming from your engine compartment, this could be a sign that your coolant is worn out and needs replacing.

Another common sign that your coolant needs replacing is if your heating system stops working. Your heating system uses hot coolant similar to how your cooling system uses cold coolant.

How to Check Your Coolant

To check your coolant, do the following:

  1. First, make sure your vehicle is off and the engine is cool. You could seriously burn yourself if you touch a piping hot radiator cap.
  2. Next, visually check the coolant reservoir and make sure the liquid is between the “Max” and “Min” fill lines.
  3. If it’s below the “Min” fill line, unscrew the radiator cap and add coolant until the liquid is above the “Min” line. Be sure not to add too much coolant. Going over the “Max” line could damage your engine. Also be sure to use coolant that is appropriate for your vehicle. You can find which coolant to use by looking in your owner’s manual.
  4. Fasten the radiator cap back on. Voila! You’re done.

How to Change Your Coolant

To change your coolant, do the following:

  1. Make sure the engine/radiator have cooled down.
  2. Find the radiator cap and remove it.
  3. Place a tub underneath the radiator and loosen the drain plug, which is normally located at the bottom left or right side of the radiator. Allow the coolant to drain.
  4. Move the tub underneath the engine and remove the engine drain bolt. This will allow any coolant stuck in the engine block to drain.
  5. Apply high temperature thread sealant to the drain bolt threads and replace the washer before putting the engine drain bolt back in place. Tighten the bolt to the level specified in your owner’s manual.
  6. Put the radiator drain plug back on. Make sure it is tight and secure.
  7. Remove the coolant reservoir and drain it. Make sure the inside is clean and then put it back in place.
  8. Use a funnel to fill the coolant reservoir with a 50/50 antifreeze and distilled water mix. Use the coolant that is appropriate for your vehicle. You can find this in your owner’s manual. When filling the reservoir, look for a maximum and minimum fill line on the reservoir container. Make sure you fill the reservoir to between these two lines, not exceeding the maximum line nor going below the minimum line.
  9. Next, use your funnel to add the coolant to your reservoir. Again, check your owner’s manual to be sure that you’re using a coolant that is compatible with your vehicle. Add the coolant until it reaches the base of the filler neck.
  10. Start the engine and let it idle outside. This allows the engine to purge any air that may have entered its system while refilling the coolant. You’ll notice little air bubble appearing at the surface of the radiator’s filler neck. You’ll want to let the engine idle until there are no more bubbles forming on the surface. This may take some time (up to 30 minutes). While doing this, make sure the engine warms up and the radiator fan comes on at least twice. You can add more coolant as needed. Check for any leaks under the vehicle as the engine idles.
  11. Once there are no more air bubbles appearing at the top of the radiator, seal the radiator cap. You’ll want to run the engine one more time and check for leaks.

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