How to Flush a Clogged Radiator? (Quick & Easy Way)

It’s been a hot sunny day; you get in the car expecting your car’s AC to cool off your soul. You turn on the AC only to know that it isn’t working. What terrible timing for your AC to hang up its hat.

Now what? Sit and blame your luck? How about you consider and think: when was the last time you flushed your radiator?

Yes, this may be the reason you drive home in sweat. That’s not it, but your engine may also break down in the middle of the road because of overheating.

A horrible nightmare to have the sun draining you while you call a mechanic, right? But don’t worry because we’ve got your back with quick steps to get things right yourself.

So, let’s dive in to learn how to flush a clogged radiator.

What You’ll Need

Before we start, let’s collect the necessary tools. Because, of course, you want to do it the right way. And the right way requires the right tools. 

So, note the following items and prepare them before proceeding to the step-by-step guide.

  • Coolant/Anti-freeze: Grab a coolant/anti-freeze specifically designed for your vehicle type. You can refer to the manufacturer’s guide for the type and amount of coolant to use.
  • Flushing Solution: You’ll find solutions available in the market that help remove the dirt and debris clogging the radiator. You can get a commercial solution or make one at home with baking soda.
  • Gloves: You’ll need a pair of gloves to protect your hands from hot coolant because safety comes first!
  • Mechanic Toolbox: Keep a mechanic toolbox ready. You’ll need it for tools like a plier or wrench to remove the radiator drain plug.
  • Funnel: To refill the radiator with new coolant.
  • Drain Pan: A dish or drain pan will also be required to collect the coolant drained from the radiator.
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Steps for Flushing a Clogged Radiator

All set and ready? Let’s get to work and drain your faulty radiator. Refer to the below steps on how to drain and flush a radiator.

Step 1: Cool Down the Engine

If you’ve just driven and experienced engine overheating, pull over and let the engine cool down before you touch anything. Always ensure that the system is cold before opening the radiator cap.

Step 2: Drain the Radiator

Place the drain pan underneath the radiator, facing the radiator cap. Now use the wrench to loosen and remove the radiator cap.

You’ll find the petcock in the radiator’s corner. Some vehicles lack a petcock and instead have a drain cap beneath the radiator.

Removing the drain cap will drain out the old coolant in the pan. If your car has no petcock, refill the radiator with high-pressure water to drain all the dust.

Doing this will fill the pan with old coolant.

Step 3: Store or Waste the Old Coolant

You’ll need to dispose of the old coolant properly. So use a funnel to keep it in a plastic bottle. You can contact a local waste management company that accepts the old coolant later.

Step 4: Add the Flushing Solution to the Radiator Cap

Once the radiator is drained, close the petcock to add a flushing solution. Now, add the radiator flush solution.

Follow the product instructions on the bottle for the right amount to add. Fill the rest of the radiator with distilled water.

Step 5: Run the Engine

Now, it’s time to circulate the flushing solution throughout the cooling solution to loosen the dirt and debris. Start the engine and run it for 15 minutes. 

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You can also refer to the bottle of radiator flush solution for the recommended time to run it.

Step 6: Drain and Flush the Radiator Again

Once you have run the engine for the recommended time, turn it off and let it cool before continuing. Place the drain pan back underneath the radiator and remove the cap.

Drain the radiator and use the garden hose to flush it thoroughly. Stop when the water runs clear.

Step 7: Add the New Coolant

Once the water is clear and you have fixed the clogged radiator, it’s time to add fresh coolant. Close the drain cap and add a mixture of coolant and distilled water, or you can also find diluted coolants on the market.

Be sure to pick the coolant according to the car manufacturer’s manual.

Step 8: Run the Engine Again

To ensure there aren’t any leaks and that the added coolant is at the right level, start the engine and let it run for 15 minutes. 

During this time, turn on your heater to ensure your engine doesn’t overheat.


That’s it for our guide on how to flush a clogged radiator! You can clean your radiator in your garage with just the right tools and a few steps.

Make sure to check the coolant every few days. Through regular checkups and maintenance, you can ensure smooth engine operation and avoid costly repairs.

Following the above steps, you can keep your vehicle’s cooling system and radiator robustly healthy. So go ahead and work your magic!

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Frequently Asked Questions (FAQs)

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