How to Flush your Car Radiator

Published: 01/26/2011 by AutoShopit

Flushing your Car Radiator

Flushing your Car Radiator

The radiator in your car is an important part of the engine cooling system. Over time, solid deposits can form in the radiator and clog up the cooling system. This will prevent it working at maximum efficiency, but you can fix this with a quick radiator flush. You might also wish to change your antifreeze or need to do other work on your car that needs the radiator emptying. Knowing how to flush your car radiator is a great skill to have and will save you money every year.


There are a few radiator flush products that you will need to get hold of before you start work. These include:

  • Screwdriver or wrench to fit radiator drain
  • Cloth rag
  • Radiator Flush liquid
  • Coolant
  • Funnel
  • Plastic dish to collect the used coolant

Once you have all these together, make sure that the engine is completely cooled down. If you are not careful, you can burn yourself on hot coolant.

Drain the Radiator

Open the radiator cap and then locate the drain plug on the bottom of your radiator and place the plastic dish underneath before you open the plug. If it will come out completely, take the plug out of the way so it does not impede the flow.

Try not to leave even a little puddle of radiator flush products on the floor as it tastes very sweet to animals but is poisonous to them.

Flush the Radiator

Wait until all the old coolant has drained and then put the plug back in place. Pour the radiator flush liquid into the radiator and fill with water. Put the radiator cap back into place and start up your car and run until it gets to operating temperature. Turn on your car heater to full and run it for another 10 minutes with the heater on.

After completing this, stop the car engine and leave it to cool. Once it has cooled, repeat the draining process for the radiator flush liquid. Again, be careful not to spill any onto the floor.

Fill it up

You are now ready to complete the process and fill the radiator with coolant. Close the plug to start and then pour the coolant mix into the radiator. Use a funnel to avoid spills. It is your choice whether you use a coolant mix, or make the mixture yourself. You are aiming to use a 50/50 mix. It may be best to measure ahead of time when learning how to flush your car radiator.

If your car contains a coolant reservoir with a separate filling location, then that will need topping up too. To finish, tighten up any caps you took off and you are done. You might wish to check your levels in after a couple of days in case you have got a little leak or had an air bubble when filling it up.

It is not a difficult job once you know how to flush your car radiator. You can easily save yourself the time and expense of a shop visit and keep your radiator and engine running in top condition.

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