How to Flush a Car Radiator for Free

Flush a car's radiator every two years.

Flushing a car radiator is a good way to extend the life of a vehicle. As sludge, gunk and rust build up in the radiator, cooling problems can occur that affect the engine life and the life of the radiator itself. At minimum, the radiator should be flushed every two years. During the flushing process, the radiator cap, hoses and clamps should be inspected to see if they need to be replaced.

Things You'll Need

• Bucket
• Sealable containers for liquid
• Garden hose
• Antifreeze
• Distilled water

Instructions

1. Park the vehicle on a flat, level surface, and set the parking brake. Open the hood and secure it to allow the engine and radiator to cool faster. Let the vehicle set for at least 30 minutes.

2. Place the bucket under the radiator's drain valve. Open the valve, and let the coolant drain out completely.

3. Move the bucket under the engine block drain plugs. Remove the plugs, and allow the coolant to drain completely.

4. Empty the contents of the bucket into a sealable container. Coolant needs to be disposed of in the same way as greases and oils, so be careful with the liquid until it can be taken to a proper recycling facility.

5. Replace the engine block drain plugs. Place the bucket back under the radiator's drain valve.

6. Run fresh water from a garden hose through the radiator until it comes out of the drain valve clean. Close the drain valve.

7. Fill the radiator with a mixture of 50-percent antifreeze and 50-percent distilled water. Do not replace the radiator cap.

8. Start the vehicle, and turn the heat controls all the way up. Allow the vehicle to run until the thermostat opens.

9. Turn the vehicle off, and allow it to cool again. Top off the radiator with the antifreeze and distilled water mixture. Replace the radiator cap.

Tips & Warnings

• Make sure to dispose of the coolant carefully and quickly. Antifreeze has a color and scent that children and animals find attractive, so it is dangerous to leave it around for too long.

References

• Castrol USA: How to Flush a Car Radiator
• Radiators.com: How to Drain, Flush and Refill Your Radiator