Why you should get a coolant flush

Why Should I Get Coolant Flush?

A coolant flush is essential because it prevents your old anti-freeze from becoming acidic. Engine coolant is a heat transfer fluid that removes excess heat from your engine.

The coolant is made from propylene glycol or ethylene and water mixed in a 50/50 ratio.

While engine coolants come in different types, picking the right type for your car is essential. The owner’s manual offers important information about the coolant, maintenance, and tune-ups you need to keep your vehicle running efficiently.

What Does Coolant Do?

Coolant, also known as radiator fluid or anti-freeze, is designed to keep your radiator cool. As expected, your engine runs hot when the weather is warm or if there is nothing to disperse the heat generated from the engine.

The excess heat generated can quickly overheat the engine and cause it to fail. When combined with the exhaust system, the coolant absorbs the heat and prevents the engine water from boiling.

The coolant also ensures that your engine’s metal, rubber, and plastic parts do not rust or deteriorate.

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Why Do You Need Engine Coolant?

Your engine produces constant internal heat as it combusts to power your vehicle. Without coolant, the heat would quickly destroy the engine.

While the coolant is mixed with water, it is not enough to cool the engine. The heat in the engine would inevitably boil the water or cause it to evaporate.

Engine coolant alleviates the excessive heat generated by your engine and ejects unwanted contaminants and debris. A coolant flush is essential to clean your system.

mechanic doing a coolant flush

What Is a Coolant Flush?

There are numerous benefits to flushing your coolant. Coolant flushes maintain your cooling system by removing unwanted debris that builds up over time. The build-up can cause corrosion, rust, and scaling in the engine.

A coolant flush pushes gallons of clean water and anti-freeze through the engine, forcing it to eject the old anti-freeze and any contaminants that may have built up in your engine.

Unfortunately, while draining the radiator rids you of a large percentage of the old anti-freeze, some coolant and contaminants still remain behind. When mixed with your new coolant, the build-up is a pollutant and may cause overheating.

You must get a full flush by forcefully removing all the old coolant to make way for the fresh fluid. In addition to removing the scaling and rust caused by the old coolant, the fresh anti-freeze also lubricates and lengthens the life of your water pump.

Additionally, when getting fresh coolant, you can prevent leaks, corrosion, foaming, and future debris build-up.

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How Do You Know You Need a Coolant Flush?

There are numerous indicators that you need a coolant flush. A major giveaway is if your car regularly overheats. When your car overheats, it indicates a leak or contaminants in the coolant system, and it could lead to damages.

Even if the coolant level is at maximum, ask your mechanic to flush the radiator to prevent overheating. You may also need a coolant flush if:

  • The anti-freeze leaks under the engine.
  • There is visible debris in the coolant.
  • Your engine emits an odd grinding or knocking noise or smell.

How Often Should You Get Coolant Flush?

There are varying opinions on how often you should flush your coolant. Some experts say annually, while others say three to five years. However, most experts agree to an annual coolant flush if the car has less than 10,000 miles.

You may need a coolant flush if your car has at least 30,000 miles or your vehicle owner’s manual recommends a schedule.

Some signs you need a coolant flush include:

  • Engine Overheating: If you notice your engine overheats while the coolant level remains intact, you may need a coolant flush. Contaminated coolant causes the engine to overheat severely. However, a coolant flush can resolve the problem.
  • Coolant Leakage: If you notice coolant leaking from your engine, it may indicate that your car needs a radiator flush. Contaminants and debris run the coolant under high pressure compromising an inlet or outlet.
  • Visible contamination: Most car owners top up their coolant and forget to flush out the old anti-feeze. As a result, it leaves room for rust build-up and scaling, contaminating the coolant over time. Always check the coolant reservoir for a consistent green or red color. A murky brown color indicates that it may be time for a coolant flush.
  • Engine Knocking: Antifreeze cools the engine increasing its efficiency. The water pump pulls the coolant and passes it around the cylinder, pulling the heat away to cool the engine. However, if the coolant is contaminated, the water pump does not work efficiently, causing the engine to overheat and knock.
  • Engine Emits a Sweet Smell: If a sweet smell comes from your engine, it is a sure indicator that your coolant is leaking. Coolant smells like maple syrup when it burns, giving a faint sweet scent from the engine bay.

How To Perform a Coolant Flush

An engine flush is relatively cheap and costs at most $40. You can change it yourself or hire an experienced mechanic to save time. The process is simple and involves the following steps:

  1. Open the radiator cap and coolant reservoir cap.
  2. Consult the owner’s manual to find the radiator drain. Use a container to collect the flushed fluid under the drain.
  3. Position the container and open the drain.
  4. Pour in the radiator flush and top up with water as indicated.
  5. Close the caps and turn on the engine. Keep the engine running for 10 minutes with the heater on high.
  6. Once the engine is cool, drain the radiator again.
  7. Refill the engine and repeat the process.
  8. Drain the radiator and add antifreeze.

When finished, clean your working area to remove spilled coolant.

car is overheating

Benefits of a Coolant Flush

  • Removes scale deposits and rust: Over time, rust and scale deposits build up, overheating the engine. They can also damage the entire cooling system.
  • Pump lubrication: The new coolant keeps the water pump running longer and better. In addition, the new coolant lubricates the water pump extending its life and performance.
  • Prevents rust: The new coolant prevents rust build-up allowing the cooling system to perform more effectively.
  • Anti-corrosive: Old coolant loses its anti-corrosive properties causing contaminants to build up in the system. Replacing the coolant cleans particles from the system maintaining its integrity.
  • Routine inspection: Typically, a coolant flush comes with an inspection of the cooling system covering the radiator, thermostat, belts, and hoses. This check helps you detect potential problems, such as leaks, in advance.
  • Prevents coolant from becoming acidic: Old coolant breaks down and becomes acidic, damaging the runner hoses, bearings in the water pump, and aluminum parts of the engine.

What Happens If You Do Not Flush Your Coolant?

If you do not flush your coolant, the radiator may negatively impact the vehicle’s performance. As a result, you may experience problems that result in costly repairs. Corrosion and sediments may also build up in the coolant system impairing its performance.

Eventually, you may have damaged gaskets, leaks, overheating and other problems that indicate your car needs a coolant flush.


Every car is different. Your car may require a different maintenance schedule depending on where and how often you drive. Check your owner’s manual to learn more about your coolant flush schedule, and contact a professional mechanic to learn more.

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