Home / Engine / How to Flush Your Car Cooling System

How to Flush Your Car Cooling System


Beyond the comforts presented by being able to regulate the temperature inside your car, your automobile cooling and heating systems are essential in averting your ride from breaking down due to extremely high operating temperatures. It’s particularly vital to check your vehicles cooling and heating systems during the weeks preceding the winter and summer seasons. But it’s usually advisable that you check these systems every time you perform routine maintenance on your car. This article explains how to flush your cooling system by yourself.

When you drive, your car’s radiator uses a mixture of coolant and water to help in lowering the operating temperature in your car’s engine system. Just like any other liquid, coolant has a propensity to breakdown over time, and this is the reason why you need to replace it once in a while.

Materials required

If you want to flush your radiator yourself, there are some necessary materials that you need to acquire. The process will require you to drain the coolant that is sitting inside the radiator. Also, keep in mind that you need to store away all fluids and keep them away from any animals.

During the replacement, there are some steps that you need to follow for a successful flush out and changing the coolant without imperiling the environment.

12 Steps on How to Flush The Entire Cooling System

Cleaning dirty coolant prevents engine from overheatingA couple of days before attempting to do a cooling system flush, you need to use a radiator cleaner. This product helps to loosen up and contaminants or debris that is accumulated in the car radiator and cooling system. Make sure you drive the car like you normally would for a few days before you attempt flushing the cooling system. Now you are ready to follow these steps:

1. Wait for your engine to cool

Before you touch any parts of your vehicles cooling system, make sure the engine is cool. Don’t touch either the upper radiator hose or the lower radiator hose. Also, don’t attempt to remove the radiator cap off if your car has been running because hot coolant can severely burn your skin.

If you were driving, then you need to park your car in a safe piece of real estate away from animals and children. Shut-off the engine and wait until the cars engine becomes cold before you begin working on the hood. The parking brake should be on.

2. Prop up your hood

After you have turned off the engine, you can start the process. It’s pretty much the same way you would want to turn off any electrical device before you start fiddling with its components. Now that the engine is cool, the cars cooling system is safe to touch, so prop the hood of your car.

Tip: Lift your car with a floor jack and place jack stands for safety measures.

3. Find your radiator pressure cap and release it

Do this cautiously. If your car has been running just before you prop up the hood, even though the engine is already cold, there is still a chance that there is a pressure build-up under your radiator pressure cap. If you release the cap quickly, the lid and the radiator content might just fly off. You should avoid this by being more careful.

4. Locate the radiator petcock that will let you drain the radiator

If you are not familiar with this technical part, then consult your user’s manual or any supplementing document for reference. The petcock is a radiator drain plug that allows the engine coolant system to drain without disconnecting the lower radiator hose. Most drain valves are usually located on the bottom right of the cooling systems.

5. Position your container underneath the petcock

The empty container will hold the drained fluid that comes out of the radiator drain valve. If your vehicle does not have a petcock or radiator drain plug, then removing the radiator hose is your only option.

Tip: Use Safety glasses for protection when flushing the system.

6. Release the petcock

Allow the coolant to drain into your container completely. Ensure that the liquid doesn’t come into contact with the ground or into a storm drain. After emptying the radiator, close the petcock and remove the container holding the drained coolant. It is usually located on the bottom of the radiator. Use a wrench to remove the drain valve.

Also, releasing the pressure cap will allow draining the radiator much faster. Make sure that you drain the coolant reservoir tank by disconnecting the upper radiator hose that runs onto the top cap.

Tip: Take the coolant residues to a local waste management facility or to an advance auto part that will recycle the fluids. Coolant has a fruity taste to it, and it is poisoning to animals.

7. Fill the radiator with water

After thoroughly draining the cooling system, now it’s time to fill the radiator distilled water. Plain water is required at this step, and not a water coolant mixture. Do not replace your radiator cap yet. Also, you can drain the reservoir tank using high-pressure water.

8. Start the car’s engine with the heater controls on high

Add the radiator cleaner into the radiator and start the engine. Depending on the amount of time specified by the manufacturer of your cleanser, you may need to leave your car idle for that amount of time, usually 20 to 30 minutes. Also, keep an eye on the temperature gauge to ensure the engine doesn’t overheat. If your car has an engine temperature warning instead of gauge, then shut it off immediately. It lights up.

9. Turn off the engine and allow it to cool completely

If the radiator is cool enough to touch, bring back your container and drain the fluid on it again by reopening the petcock, which is generally under the radiator. After successful draining, close the petcock.

10. Fill the radiator with water for the second time

This is very important as it will clean your radiator from mineral deposits and gunk thoroughly. Start your vehicle again and leave the engine running to idle for around 5 minutes. After the 5 minutes, turn off the engine and drain off the water from the radiator into your drain pan container and then close the drains. Place your automobile back onto the ground.

Tip: Clean any debris before refilling the system with fresh coolant.

11. Bring your new coolant and follow all the instructions provided in the cars owners manual

Most vehicles need a 50-50 mix of water and coolant. Fill with the amount of antifreeze according to what the car manufacturer owners manual instructions state. The mixture should reach the ‘MAX’ fill line on the coolant recovery reservoir or cover the fans in the radiator. Try not to go over the coolant level.

12. Disperse the coolant and water evenly throughout the system and finally replace your radiator’s cap

Keep the engine running with the heater controls on high until the temperature gauge reads normal range. Now that you completed the system flush, you won’t need to change the coolant for a long time, although you want to check the coolant level If you take your vehicle for regular car maintenance.

Heres a complete video from Chris Fix that explains  how to super-flush you cooling system:

Benefits of flushing a dirty cooling system

The above steps highlight an overall detail way of how to flush your cars cooling system. There are plenty of benefits that you get when it comes to flushing or having a complete system flush. Whenever you bleed the system, it removes contaminants that have been accumulating during the lifespan of your vehicle, when I flushed my radiator for the first time the coolant that came out wash really disgusting.

Another benefit when you flush the radiator is that the new coolant lubricates and extends the life of the water pump. Also, fresh coolant flushes old rust that is build up in the heater core. The new antifreeze also protects against foam and rust. Some experts recommend flushing the cooling system at least once every couple of years when your vehicle has accumulated too many miles.

10 Tips When Flushing the System

  1. Use distilled water because tap water can have some contaminants.
  2. Allowing the engine cool off is an essential requirement.
  3. Apply the flush solutions or products several days before you get a system flush.
  4. Store and recycle all the waste that drains from the radiator.
  5. Removing the cap will cause air bleeds, and the fluids will drain faster.
  6. Use jack stands to lift cars trucks.
  7. Check for any leaks on the engine block if your vehicle is overheating.
  8. Locate the petcock and place the drain pan under it to catch the fluids.
  9. Replacing the thermostat and the head gasket is recommend when you flush the radiator.
  10. Check the temperature gauge at all times when you leave the car running.


If you follow these steps well, you will successfully flush out your entire cooling system. Overheated engines will require extra professional auto repair services. A common cause of why an engine overheats is a coolant leak. Radiator flushing can be challenging; that is why we suggest you use a local automotive repair shop. Replacing the old coolant can prevent the engine from overheating.

Check our related articles for interior painting and exterior painting suggestions. Some pest control and auto repair companies will recycle the fluid residue. Also, it is crucial that you take waste management and home security serious because animals can get harmed. A common sign that you need to replace the coolant is if your car AC stopped working.

Make sure to check the owners manual for the amount of antifreeze required. Check the condition of the head gasket just to make sure you don’t have to stop leak from the engine. Car repairs can take time, so be patient. Coolant flushing or radiator flushing is a must when buying used cars.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Notify of
This div height required for enabling the sticky sidebar