How to Clean Out a Car Radiator? – A Detailed Guide

Written by Howell Crist / Fact checked by Sam Howard

 how to clean out a car radiator

Car radiators possess the solution to regulating your car engine’s temperature. Together with its component thermostat, it detects overheating and absorbs the extra heat by releasing water and coolant.

However, this cooling system is prone to being dirty as time passes by. This may build up, causes clogging, and renders the engine to overheat and get damaged.

It is essential that your car engine is always functional so monitor its temperature by treating car radiator cleaning necessary. Continue reading and learn the detailed steps as well as the needed materials on how to clean out a car radiator by yourself effectively.

Ways to Clean Out a Car Radiator

What is the best way to clean a radiator? This article answers with baking soda and vinegar which are the superstars of the three economical and effective ways enumerated below.

These could be done without removing any parts from your car making it doable by yourself. Just remember to always turn your car off and have your car engine cooled down before doing anything.

#1 Homemade Radiator Cleaning Spray


Cleaning sprays are expensive when bought readily from stores. If saving money is your plan, your car radiator cleaning solution should have a content of either vinegar or baking soda.

These two help clean outside of a radiator by removing corrosion, dirt, and rust. Evidently, this achieves a prominent clean car radiator exterior.

What to Prepare:

  • Water
  • Vinegar or Baking Soda
  • Gloves
  • Toothbrush
  • Hose
  • Step 1: Create the radiator cleaner spray solution

Add 5 teaspoons of baking soda to a liter of water and mix it well until it becomes a homogeneous liquid. As an alternative, you can add equal parts of water and vinegar to create the same cleaning solution through an acidic approach.

  • Step 2: Spray the solution

Aim and spray enough amount onto the dirty areas. Make sure you do not overspray it, just enough to soften the build-ups, to avoid splashes to the other mechanical parts.

  • Step 3: Brush the affected areas

Using a toothbrush, gently brush and apply enough force to remove the sediments away. It is tricky to clean aluminum radiator fins because they easily get bent so do not overdo it.

  • Step 4: Spray the radiator fins

Spraying down with a hose is a complementary step in cleaning car radiator fins. You could also clean behind a radiator the same way but control the pressure of the water to avoid damage to the fins.

  • Step 4: Air dry

Lastly, don’t use a cloth to dry the radiator because the fabric might get stuck between the fins. Air dry it instead.

#2 Vinegar Solution as Radiator Flush


Note that vinegar contains acetic acid which might cause corrosion on metals if used too much and not properly flushed away. It is not recommended to use in an old radiator

However, it is proven to be effective in aiding a clogged radiator. Flushing with vinegar clears out debris and sediment build-ups even those accumulated over a long time.

What to Prepare:

  • Distilled Water
  • Vinegar
  • Rubber Gloves
  • Safety Glasses
  • Containers
  • Step 1: Create the solution

The solution should have 50% of distilled water and 50% of vinegar. You can directly fill this mixture into the radiator while considering the proportion.

  • Step 2: Drain the radiator

Place a container under your car radiator and open its drain cock. Do not forget to use rubber gloves and safety glasses to avoid physical contact with the chemical.

  • Step 3: One to two days of soaking

Clean the inside of the radiator by letting the solution soak for 24 to 48 hours. Generally, an overnight is enough to clean.

  • Step 4: Drain the cleaning solution

Using a container, drain the cleaning solution. Meticulously check that all vinegar is removed.

  • Step 5: Rinse with distilled water

Rinsing the car radiator with distilled water is crucial because unflushed vinegar might cause corrosion inside. Repeat this step until satisfied.

  • Step 6: Drain the radiator again

Make sure to remove all remaining liquid and solid residue before proceeding. Dispose all collected liquids properly.

  • Step 7: Add coolant

Depending on your car’s manual, add the appropriate radiator coolant.

#3 Baking Soda Solution as Radiator Flush


Just like vinegar, frequent usage of this product could also corrode the radiator. However, its benefits outweigh the cons which include its capability as a car radiator cleaner.

What to Prepare:

  • Distilled Water
  • Baking Soda
  • Rubber Gloves
  • Safety Glasses
  • Containers
  • Step 1: Create the solution

Use the same formula above. Mix five teaspoons of baking soda for every liter of distilled water and dissolve.

  • Step 2: Drain the radiator

Use a container to drain the fluids from the radiator. Avoid physical contact with the chemical.

  • Step 3: Fill the radiator

Fill the radiator with baking soda solution. Wait for 5 minutes.

  • Step 4: Run the engine

Turn your car on for 5 to 15 minutes. This heats the solution inside the radiator creating a chemical reaction that aids the clogging.

  • Step 5: Drain the radiator again

You may use the same container but make sure to do it carefully by avoiding physical contact with the liquid.

  • Step 6: Rinse the radiator

Rinse it with distilled water. You may repeat steps 3 to 6 until the water is clear.

  • Step 7: Drain the radiator again for the last time

After draining, dispose of all the liquids properly.

  • Step 8: Apply coolant

Lastly, fill in the recommended coolant to use in your car radiator.

Steps to Flush a Radiator


  • Step 1: Turn off your car engine and cool it down before proceeding.
  • Step 2: Protect yourself by wearing rubber gloves and safety glasses.
  • Step 3: Prepare and dilute the homemade radiator flush you chose- vinegar or baking soda.
  • Step 4: Drain the old antifreeze by using any container under the drain cock opening.
  • Step 5: Pour the cleaning solution into the fill hole of your car radiator and wait for the chosen solution’s required time to soak.
  • Step 7: Turn your car engine on and run it for 5 to 15 minutes (baking soda solution) or just let the solution soak overnight (vinegar solution).
  • Step 8: Turn your car engine off and drain the cleaning solution.
  • Step 9: Fill the radiator distilled water (as recommended).
  • Step 10: Run your car engine for at least 5 minutes.
  • Step 11: Drain your car radiator again.
  • Step 12: Add the car’s recommended coolant to the radiator.
  • Step 13: Finally, properly dispose of the liquids you have collected.


Can I flush my car radiator at home?

You can flush the car radiator at home but know how to do it safely both for yourself and your car. You can make use of the homemade radiator flush mentioned above.

Signs to know when I need a radiator flush

Feel your dashboard if it has a high temperature. This is a possible indicator that your car engine is overheating.

As explained above, engine overheating says something about your car radiator core. It might need to flush clogged debris to function properly.

An unusual sugary or butterscotch smell present in your car is also an indicator. The coolant contains molecules of ethylene glycol which produces a sweet aroma when exposed to heat.

How often should I flush my radiator?

It depends on your car’s manual but if you see the appearance of rust or corrosion on your car radiator, flush it as soon as possible. Have it done by a cleaning service for severe cases.

Also, your car radiator should be flushed every five years or at least once for every 100 000 miles you travel.

Advantages of flushing a car radiator

Flushing your car radiator makes your car engine free from damaging itself. This costs you way less than replacing your car engine with a new one.

Specifically, this prohibits sediment formation by removing contaminants and build-ups within the cooling system. This way it avoids clogging and functions productively.


Now that you know how to clean out a car radiator, make use of that sitting vinegar and baking soda in your pantry, and apply your learnings in your car. You can now treat your car radiator as a best friend who also takes care of your car engine.

Anywhere at any moment, nobody wants a faulty car engine, right? So if you find this article helpful, it would be kind to share it and save a friend!

5/5 - (3 votes)

Our chief editor is Sam Howard. The vast market of car care necessitates extensive research. He entered the market, experienced the service, and reported customer feedback in order to provide the best advice and content to car owners. We have faith in him to turn our website into a reliable resource for all car owners.

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