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How to Flush a Radiator

How to Flush a Radiator

A radiator is the heart of your car’s cooling system, which allows water or coolant to circulate through small tubes (cooled by incoming air) to various sections of the engine. Radiator fluid or coolant helps to disappear the engine’s excessive heat and prevents overheating and engine failure. This liquid circulates the heated engine, cooling the metal parts by transferring heat to the radiator, where it is cooled before returning to the engine again.

But sediment build-up from heated metal and evaporated water can clog the radiator over time which can cause your car to overheat. Radiator fluid, like most fluids that pass through engine components, accumulates pollutants over time. 

This can lead to radiator corrosion, a malfunctioning cooling system, damage to engine components, and, in the worst-case scenario, engine failure if not cleaned. While maintenance work such as radiator flush is a minor and easy job but if ignored for a long time, it can lead to major and costly consequences. That’s why flushing the radiator and refilling it with new coolant after the recommended period or distance in the owner’s manual is mandatory. 

Signs That Antifreeze or Coolant Needs to Be Changed

  • Your vehicle’s engine is running hotter than usual
  • The antifreeze or coolant light is on in your vehicle’s dashboard and shows a low coolant level. 
  • Unusual steam or smell similar to boiling maple syrup is coming from your engine
  • A grinding noise is coming from under your car’s hood.
  • Your heater isn’t working.

Equipment and Materials Needed

  • Rubber gloves 
  • Safety glasses
  • Carjack and jack stands
  • Drainage pan or Drip tray
  • Screwdriver or socket wrench
  • Distilled water (2-3 gallons) 
  • Radiator cleaner (as suggested by the manual’s guide) 
  • Antifreeze or coolant

Materials to Avoid While Flushing a Radiator

  • Vinegar should be avoided because acetic acid causes metal to corrode.
  • Bleach or items containing it should never be used since sodium hypochlorite (bleach) corrodes metals like steel and aluminum. Also, cause damage to the vehicle’s engine head, as well as destroys rubberized gaskets and seals. 

How to Flush a Radiator

A radiator flush ensures that your coolant system protects your engine as effectively as possible. It prevents rust and other pollutants from damaging metal engine parts. It also helps to prevent your engine from overheating when it is operating and from freezing while it is not.

Note: Put on your rubber gloves and safety glasses.

Setting Up the Car 

setting up the car
  1. Set the car on the parking brake so that it won’t move while you flush the radiator.
  2. Use a car jack to lift the metal frame on the underside of your car and support it with two jack stands
  3. It will be easier for you to reach beneath the vehicle and fit the drainage pan below the vehicle.
  4. Place a drainage pan or drip tray underneath the radiator. 

Locate the Radiator

locate the radiator
  1. Wait at least 30 minutes after driving your vehicle before beginning to flush the radiator. 
  2. Raise your hand over the engine block to check how warm it is. Or check coolant temperature is in the blue area or below the meter. 
  3. When it is cool enough start by locating where the radiator cap is. 
  4. Lift your vehicle’s hood and search for a flat, finned metal region at the front. 
  5. The radiator is a long, narrow metal tank located near the engine in front of your vehicle.
  6. You will see a round cap above a radiator, usually made of metal, t
  7. You may see “radiator coolant” or something like that written on the cap.
  8. To loosen and remove the cap, turn it slowly counter-clockwise
  9.  And remove the cap

Draining Out the Old Anti-freeze

  1. Check whether you have placed the drain pan right beneath the radiator or not.
  2. Go underneath and release the drain plug. The metal tank will have a small opening at the bottom on the driver’s side.
  3. There will see a little tiny thing known as a petcock valve or drain valve. 
  4. If it won’t come out easily use a screwdriver or socket wrench to open it.
  5. When you remove the petcock valve you can see the fluids coming out.
  6. Let all the fluid get out of the radiator. 
  7. Close the drain valve once the liquid has stopped flowing and tighten it up. 

NoteDon’t let antifreeze trickle down a drain or into the street can be hazardous to the environment.

Cleaning the Radiator With Cleaner and Distilled Water

Cleaning the Radiator With Cleaner and Distilled Waterr
  1. Now we will put distilled water and radiator cleaner into the radiator from where you removed the pressure cap in the first place.
  2. To ensure that all of the cleaner and water get inside, use a funnel. 
  3. First, pour the entire cleaner bottle into the radiator, followed by 1 gallon of distilled water. Make sure the water is distilled and not filtered.
  4. After you’ve filled the radiator, put the pressure cap back.
  5. Then, for about 5 minutes, run the engine with the heat set to maximum by turning the key in the ignition.
  6.  It allows the cleaner and water mixture to circulate through the cooling system and clean it.
  7. Allow 15 minutes for the engine to cool after turning it off. 
  8. Open the pressure cap and petcock to drain the radiator. 
  9. Make sure the drainage pan is underneath the petcock to catch the cleaner and distilled water. 
  10. The water may have turned brown or rust-colored after working through the entire cooling system. 
  11. Repeat the whole process until the water comes out clean. But instead of radiator cleaner now use just distilled water.
  12. Once the water is clear, flush the radiator one last time to verify it is clean. After the coolant flush, close the petcock valve. 

Refilling the Antifreeze in the Radiator 

Refilling the Antifreeze in the Radiator 
  1. The amount of new antifreeze to be refilled in the radiator is determined by the vehicle’s manual’s instructions. 
  2. However, it’s normally half a gallon of new antifreeze combined with half a gallon of distilled water, which you can mix in a bucket
  3. You can also use a ready-to-use 50/50 antifreeze /distilled water blend.
  4. Remove the pressure cap from the radiator and pour the antifreeze mixture into it.
  5. To ensure that all of the solutions make it inside, use a funnel.
  6.  Make sure the radiator reservoir is filled. And put the pressure cap on it.
  7. Again start your vehicle and run the engine for 5minutes to pull the antifreeze down to the cooling system.
  8. Let your car cool down for 15 minutes before removing the cap
  9. Then check to determine if the antifreeze within the radiator is level with the fill line. If not add more solutions.
  10. If there is any extra solution left you can store it in a container and reuse it later. 

Benefits of Radiator Flush

  • Removes rust and other dust deposits
  • The coolant will Lubricate the water pump and increase its life span.  
  • Removes all the contaminants
  • Inspection of your cooling system
  • It will prevent foaming and rust in the system. 

How Often Should I Flush My Radiator?

Check your vehicle’s owner’s manual to find out exactly how often a radiator flush is recommended for your model.

Generally, for most vehicles, it is recommended a radiator flush every 30,000-50,000 miles, or every 2-5 years. And the total cost varies from range $35.00 to over $100.00.