How to Flush a Car Radiator | Cleanipedia ZA (2023)

Signs you need to clean your radiator:

Find out if it's time to learn how to clean a car radiator by checking for these signs:

  1. Your car keeps overheating.

  2. Coolant is leaking beneath your car.

  3. You hear a knocking noise in your engine.

Even if you take good care of your vehicle, there are going to be parts that just don’t work as well over time. Luckily, you can clean and maintain some of these parts - like the radiator - yourself. Let's start by learning how to clean a car radiator.

Wear rubber gloves to keep your hands clean and safety glasses to stop any fluid splashing into your eyes.

Why is it important to know how to flush a car radiator?

Car running a little hotter than usual? Smoke coming from under the hood? It’s probably your radiator.

(Video) How to SUPER FLUSH your Cars Cooling System

A car radiator can become clogged with calcium and rust over time, stopping regular function. This can cause permanent damage to your engine if it goes untreated, leading to costly repairs in the future. Learning how to flush your radiator helps prevent these blockages and any further damage.

How to flush a radiator

Not sure how to use radiator flush products? There are a number of commercial options designed to flush your car's cooling system by getting rid of build-up. They should all have directions printed on their packages but most will work in a similar way to the following steps:

  1. Stop the engine and let it cool completely.

  2. Place a bucket beneath the radiator - this is to catch any debris and fluid as it comes out of the radiator.

  3. Bleed the radiator by opening the bleed valve.

  4. Close the bleed valve once the radiator has been drained but before adding your flushing product.

  5. Open the cap of your car’s radiator and add the flushing product as directed on the bottle.

  6. Leave the flush in the system and heat it for the time specified on the bottle. This is usually around 10-15 minutes.

    (Video) How to Flush a Radiator | DIY Car Repairs

  7. Open the bleed valve and allow the flush to drain into the bucket.

  8. Continue to repeat steps 3-7 until the water drains clear.

  9. Flush one last time with distilled water only. Close the bleed valve firmly once finished.

  10. Refill the radiator with coolant.

After flushing your car's radiator, it's best to run the car for a short while to check for leaks. You may also want to take it on a short test-drive locally before making any long journeys.

How to clean a radiator ... with baking soda

Looking for something a little more homegrown? You can actually make a homemade solution to clean a radiator in your car using baking soda!

  1. Start the same way as wtih the commercial product - by cooling your engine and draining all coolant from the radiator.

  2. Mix baking soda with water. You'll want approximately 5 teaspoons of baking soda per 1 litre of water.

    (Video) How to use - Radiator Flush Additive Explained

  3. Add the solution to your cooling system and run the engine until it’s hot.

  4. Drain the system before flushing it again with distilled water.

  5. Fill with new coolant.

Cleaning your car radiator is just one way you can make sure your vehicle lasts for many years to come.

Frequently Asked Questions

Can I flush my radiator myself?

You absolutely can! Just make sure you wear protective gear like rubber gloves for your hands and safety glasses to avoid any fluid splashing into your eyes.

Do you really need to flush your radiator?

Over time, a car radiator can begin to work less efficiently than when it was brand new. When the signs start to show, it may definitely be time to give your radiator a flush to enable it to begin working better.

What is the best thing to use to flush a radiator?

(Video) How to flush a radiator

Flushing a radiator is a simple enough process. Just make sure you have the right equipment and enough time to get the job done well. Check out the article above on how to flush a radiator, step-by-step.

How do you flush a car cooling system?

Whether you’re using a flushing liquid or baking soda, there are a few ways to flush a radiator or cooling system. Read the article above for more handy tips.

How do I know when I need a radiator flush?

There are a few signs to look out for that will tell you that it’s time to flush your car radiator.


How do I completely flush my coolant system? ›

  1. STEP 1 - Safety first. ...
  2. STEP 2 - Press down on the radiator cap, slowly turn it counter-clockwise until it hisses, wait until the.
  3. STEP 3 - Place a large container under the drain valve at the bottom of the radiator. ...
  4. STEP 4 - Loosen the drain valve and allow the coolant to completely drain out.

Can I flush my car radiator myself? ›

Flush the Radiator

Remove the radiator cap and pour distilled water into the radiator until full. Replace the cap, then start up the vehicle and let it run for 10 to 15 minutes. This will work the distilled water into the engine, flushing out any loose debris or corrosion along with the last of the old antifreeze.

How much radiator flush do I need? ›

Most agree that if you have a new car with less than 10,000 miles on it, there should be no need to do a radiator flush for at least a year. If there are no other signs that you need to flush out your radiator, you should do it at least every 30,000 miles or according to your owner's manual recommended schedule.

Will a car run better after a coolant flush? ›

A mechanic will then finish the coolant flush by adding fresh antifreeze to your engine along with a conditioner that will keep it protected for longer. This process improves the health and protection of your vehicle, so you will likely notice an immediate boost in engine cooling and performance following this service.

How do you test if a radiator is clogged? ›

5 Symptoms Of A Clogged Or Bad Car Radiator
  1. Temperature Gauge Reading Higher Than Normal: The temperature gauge indicates the temperature of a car coolant. ...
  2. Radiator Leaking Coolant: ...
  3. Radiator Hose Troubles: ...
  4. Coolant Color Change: ...
  5. Radiator Fins Bent or Broken:
Jul 28, 2022

Is Vinegar a good radiator flush? ›

To avoid damaging your radiator and potentially your engine, your choice of cleaning product is important. Avoid using vinegar, because the acetic acid makes metal susceptible to rust. Additionally, bleach should never be used, because sodium hypochlorite (bleach) will corrode metals such as steel and aluminum.

Can you do a radiator flush with tap water? ›

The short answer is no; you can't mix tap water with engine coolant. Antifreeze should not be mixed with water replacing your engine coolant. Distilled water can work, but it is not ideal.

Do I have to use distilled water to flush radiator? ›

As it chemically removes electrons from the metals of cooling system components, distilled water eventually does extreme damage that could lead to cooling system failure. So what's the answer? Softened water.

Can I use Dawn to flush my radiator? ›

Never ever do such things as adding dish soap to the coolant system to flush. Any soap in the system may start eating the engine blocks and could cause a catastrophic failure.

How long should you leave radiator flush in? ›

Let your engine idle with the radiator flush inside for at least 10 minutes, but time and weather permitting run your vehicle for 3-6 hours with the radiator flush and water solution in your cooling system. This will provide a deep clean and restore your cooling system to top efficiency.

How long do radiator flushes take? ›

A trained mechanic can perform a radiator flush in about 30 minutes using a commercial coolant flush and fill machine. Without a machine, a radiator flush takes about two hours. You'll need to allow additional time for any other services performed at the same time, such as radiator leak repair or inspection.

How long should you use radiator flush? ›

As a general rule of thumb, you should get a coolant flush every 30,000 miles or three to five years, whichever comes first. Your car's owner's manual should also outline a more specific interval depending on the manufacturer.

Can you top off coolant or do you need to flush? ›

The simplest way to avoid overheating is to service the system every two years or according to your car manual recommendations. Flushing the coolant and replacing it with fresh fluid every two years or 30,000 miles is a good rule. While you perform this service, inspect the hoses and radiator cap for wear.

Will radiator flush stop overheating? ›

To fully clean your system, it's vital to fully evacuate the old coolant so that the new antifreeze doesn't blend in. Therefore, coolant flush keeps your radiator in optimal working condition and minimizes overheating and high-temperature gauge risk.

How many years does coolant last? ›

HOW OFTEN SHOULD YOU FLUSH THE COOLANT? Depending on the vehicle and the coolant, the average time between flushes is two years or 30,000 miles for silicated coolants and up to five years or 100,000 miles for an extended drain coolant.

How do I know if my radiator has water circulating? ›

One way to check for proper coolant circulation is to check the upper and lower radiator hoses. The upper radiator hose should be hot, around 190–200 °F. (The safest and most accurate way to get this temperature reading is with an infrared thermometer.)

How do I know if my air is trapped in my radiator? ›

Signs and symptoms of radiator airlock include:
  1. Overheating during normal driving.
  2. Heater not functioning correctly.
  3. Reduced performance.
  4. Radiator leakage / losing coolant quickly.
Apr 6, 2021

What are the signs of a blown radiator? ›

Four Signs You have a Bad or Failing Radiator
  • Your vehicle is overheating. If your vehicle constantly overheats, especially under normal driving conditions, this is one of the most common signs that your radiator is bad or failing. ...
  • Your vehicle is leaking coolant. ...
  • Sludge build up in your radiator. ...
  • Low coolant levels.
Dec 19, 2016

Can I use coke to flush my radiator? ›

It sounds crazy, but Coca-Cola works great for cleaning radiators. One or two fills with the coke (let it sit for 2-4 minutes) and rinse thoroughly with distilled water. The acidity of the coke removes the gunk in the radiator as well as a fair amount of loose rust.

What liquid is used to clean radiators? ›

The most preferred composition as a radiator cleaning material includes approximately 48% by weight distilled water, 2% by weight of butyl ethylene glycol base, and 25% by weight of the hydrochloric acid-based composition as described above that has a pH of less than about 1.0.

Can I use bottled water to flush radiator? ›

What Type Of Water Is Best? If you don't have coolant available, you should top up your radiator with the highest quality water that you have. Ideally, this would be distilled water. You can also use bottled water or tap water.

Is Boiling water the same as distilled? ›

No, they aren't the same. Boiled water is simply water that has had the temperature increased until it reaches its boiling point. This kills a host of bacteria that can make a person sick. Distilled water is water that has been stripped of all impurities, including minerals and microorganisms.

What happens if you overfill coolant? ›

Most of the time, excess coolant is expelled from an overflow hose. You'll likely see a puddle of coolant beneath your car if this has happened. In worst case scenarios, overfilling your antifreeze tank can lead to electrical damage if overflow comes into contact with engine wiring.

What is the difference between a coolant flush and a radiator flush? ›

What is a Coolant Flush? A Coolant flush or sometimes known as a radiator flush includes the complete removal of fluid from the system. Some shops perform a cooling system service that simply drains the system and replaces the coolant.

Can you leave engine flush in over night? ›

Can I leave the engine flush chemical overnight? Engine flush chemicals should not be used for a long period (more than 5-10 minutes). just use it right before an oil change. Longer applications of chemical additives used for engine flush can damage the engine.

How long does a full coolant flush take? ›

A trained mechanic can perform a radiator flush in about 30 minutes using a commercial coolant flush and fill machine. Without a machine, a radiator flush takes about two hours. You'll need to allow additional time for any other services performed at the same time, such as radiator leak repair or inspection.

Do you have to remove thermostat to flush coolant? ›

No, it is not necessary to remove the thermostat. In fact, some cars you don't want to remove the thermostat while running the vehicle. The reason for this is that the thermostat can be used to direct coolant flow.

Is it OK to flush coolant with tap water? ›

Can You Mix Tap Water With Engine Coolant Safely? The short answer is no; you can't mix tap water with engine coolant. Antifreeze should not be mixed with water replacing your engine coolant. Distilled water can work, but it is not ideal.


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