How to Clean a Car Radiator? – Easy Methods You Can Try at Home

Written by

Bruce Sonnier


Marcus Dutton

how to clean a car radiator

If the radiator is left uncleaned, its fins can get clogged, and the engine may overheat and eventually get damaged. Read on to know how to clean a car radiator, and you’ll be able to do it in a snap. The best way to clean a radiator would depend on your cleaning need, which is either of the two:

  • Clean the radiator fins – done when dirt and debris accumulate on the fins, which involves spraying solution, brushing away dirt and debris, and rinsing.
  • Flush the radiator – done at least every 30,000 miles or as recommended in your car manual, which involves draining out the coolant, flushing with a solution, flushing with water, and refilling the coolant.

Cleaning Radiator Fins


What You Need

  • Radiator Cleaner – When cleaning a radiator, it would be best to use a commercial cleaner specifically designed for radiator cleaning in order to properly clean without causing any damage. Some other cleaners like vinegar and bleach can cause rusting and corrosion.
  • Water – You would need water for diluting the radiator cleaner.
  • Big Container – A big container would come in handy for diluting the radiator cleaner.
  • Spray Bottle – You would use it for applying the diluted cleaning solution.
  • Soft-Bristled Brush – Radiator fins would require gentle cleaning. So a soft-bristled brush would be perfect for the job.
  • Flathead Screwdriver, Ice Pick, Barbeque Skewer, or Toothpick – These can be used to straighten the radiator fins if some of them get bent while cleaning.
  • Hose – Particularly one that can work in low pressure would be required.

Step 1: Let the Radiator Cool Down

For safety, the first step you should take when you clean an aluminum radiator is to cool it down. Make sure it’s cool to touch before starting to clean the fins.

Step 2: Dilute the Cleaning Solution

The cleaner would have to be diluted first, which you can do in a large container. The water to the cleaner ratio for diluting would depend on your cleaning product, so check the product instructions on the product’s back label. Then pour the diluted cleaning solution into a spray bottle.

Step 3: Clean the Radiator Fins With the Solution and Soft-Bristled Brush

Spray the cleaning solution onto the radiator fins. Then, gently brush away the dirt and debris accumulated in the radiator fins with the soft-bristled brush. Be careful not to bend the radiator fins.

Step 4: If Some Radiator Fins Get Bent, Straighten With a Flathead Screwdriver

Suppose you may have accidentally bent some of the radiator fins. In that case, you can put them back into shape by gently straightening them with a screwdriver. Or some alternatives you can use for straightening them are an ice pick, barbeque skewer, or toothpick.

Step 5: Rinse the Radiator Fins With a Hose

Rinse the radiator gently with a hose set at low pressure. If you see that water doesn’t appear clear after you rinsed it, repeat steps one to three.

Step 6: Let the Radiator Fins Air Dry

Finally, airdry the radiator fins.

Flushing a Radiator


What You Need

  • Catch Pan or Bucket – Prepare these items so that you wouldn’t be making a mess. Also, you can ensure that the harmful chemicals won’t soak through the ground when you drain and flush the radiator with a catch pan or bucket for collecting the substances.
  • Flushing Solution – A flushing solution can effectively eliminate the contaminants and debris in the radiator. For best results without causing any damage like rusting and corrosion, use a commercial solution specifically designed for radiator flushing and avoid potentially damaging substances like vinegar and bleach.
  • Distilled Water – Diluting the flushing solution would also be necessary for flushing the radiator. It would be best to dilute with distilled water rather than tap water.
  • Big Container – You can dilute the flushing solution in a big container.
  • Coolant – It’s a fluid that helps lower the heat in the engine. You should consult the manual for your car or your local dealership on what coolant to use to make sure that you use a coolant that’s best for your car.

Step 1: Let the Engine Cool Down

The engine has to be cooled down before you flush the radiator to be safe. So you first have to ensure that it has completely cooled down.

Step 2: Put a Catch Pan or Bucket Underneath the Radiator

Place it directly underneath the radiator’s petcock valve or drain plug. This will catch all the substances flowing out the radiator.

Step 3: Drain Out the Coolant

Open the petcock valve or drain plug to allow the coolant to drain from the radiator. Once all the coolant has been drained, close the petcock valve or drain plug.

Step 4: Dilute the Flushing Solution

You can prepare your flushing solution in a large container. Just follow instructions for diluting on the product’s back label.

Step 5: Pour the Flushing Solution Into the Radiator

Once your flushing solution is all set, open the radiator cap and pour the solution into the radiator. Then let the engine run with the heater level set on high while you leave the solution in there to take effect on the system for as long as the product instructions suggest, which is usually 10-15 minutes. If you notice the engine getting hotter than normal on the temperature gauge, immediately shut it down to prevent damage.

Step 6: Drain Out the Flushing Solution

Let the engine cool once again. Then open the petcock valve or drain plug to let the flushing solution drain out from the radiator.

Step 7: Pour Distilled Water Into the Radiator

Again close the petcock valve or drain plug. Pour distilled water into the radiator. Then, run the engine once again with the heater level set on high. This step allows the water to flush the radiator for about 10 minutes, depending on the product instructions. Remember to check the temperature gauge to ensure that the engine doesn’t get too hot. You should immediately shut it off when it does to prevent damage.

You can repeat the process to ensure that all of the cleaning solutions has been rid of. Then close the petcock valve or drain plug again.

Step 8: Refill Coolant Into the Radiator

Before you refill the radiator, let the engine cool first. And you should also dilute the coolant in a 50/50 ratio before pouring it in.

Step 9: Monitor the Cooling System and Resolve Issues

It would be wise to monitor the cooling system after refilling it with coolant to prevent overheating. To do that, start the engine and check the temperature gauge for a prolonged duration.

Suppose you notice that the engine gets too hot. In that case, you must immediately shut it off and resolve whatever is making it hot. It could either be a low coolant level in the radiator, or air may have gone inside the system while you underwent the flushing procedures.

If the cause of too much heat is the former, simply add more coolant to the system. But if it’s the latter, consult the factory repair manual for the recommended procedure for bleeding out the air, or you may also use compressed air and vacuum-fill tools.


One of the essential regular maintenance of a car is to clean out a radiator. Remember to regularly do the procedure for how to clean a car radiator to prevent problems with your engine.

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