Rust Removal From a Cooling System

by Mary LougeeUpdated July 10, 2023
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A radiator uses a mixture of distilled water and antifreeze to keep an engine cool. The antifreeze has lubricating components to keep rust from forming in the radiator and the entire cooling system. After a period of time, antifreeze breaks down and does not cool or lubricate the system as well. This increases mineral deposits in the radiator, reduces the flow of liquid and creates rust inside. Flushing the radiator with a radiator cleaner removes rust and deposits so it can operate properly.

Things You'll Need:

  • Bucket
  • Screwdriver
  • Radiator cleaner
  • 50/50 antifreeze
  • Radiator rust inhibitor

1. Park the car on a level surface

Park the car on a level surface. Turn the engine off and open the hood. Let the engine cool completely.

2. Push in and turn the radiator cap one-half turn to loosen it

Push in and turn the radiator cap one-half turn to loosen it. Pull the cap straight off. Place a bucket under the radiator petcock. Turn the petcock one-half turn to open the valve and let the radiator drain completely.

3. Insert a screwdriver into the hose clamp on the radiator overflow container

Insert a screwdriver into the hose clamp on the radiator overflow container. Turn the screw counterclockwise to loose the clamp and pull the hose off. This will allow the old fluid to drain from the container. Push the hose back on after draining is complete and tighten the screw clockwise to secure the clamp.

4. Close the petcock on the radiator bottom

Close the petcock on the radiator bottom. Pour a bottle of radiator cleaner into the radiator fill neck at the top. Follow the package directions for adding additional water to the radiator. Turn the engine on and let the car idle according to the package directions.

5. Turn the car off and let the engine cool

Turn the car off and let the engine cool. Drain the radiator cleaner from the car as before. Close the petcock.

6. Pour 50/50 antifreeze into the radiator neck to the neck bottom

Pour 50/50 antifreeze into the radiator neck to the neck bottom. Turn the car on and let it idle. Squeeze the top and bottom radiator hoses to burp the system and remove any air bubbles in the radiator. The bubbles will be apparent in the radiator neck and the volume of antifreeze will fall.

7. Pour 50/50 antifreeze into the radiator overflow container

Pour 50/50 antifreeze into the radiator overflow container to the “hot” mark on the tank.

8. Pour a bottle of radiator rust inhibitor into the radiator neck

Pour a bottle of radiator rust inhibitor into the radiator neck. Continue adding antifreeze as the level diminishes in the radiator, until the level remains constant at the bottom of the neck.

Tips

50/50 antifreeze is a 50 percent distilled water and antifreeze mixture.

Antifreeze and rust inhibitors are available at auto parts stores.

Flush the radiator at intervals according to the car manufacturer’s guidelines in the vehicle user manual.

Video showing how to remove rust in your cooling system:

Helpful comments on this video:

  • Use distilled water, tap water has minerals in it that will cause it to rust again.
  • Run it for a week not “ a couple hours “ to get the results you need.

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