How to Flush a Radiator

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A radiator is the part of a vehicle that keeps the engine cool. Once sludge and rust build up inside the radiator it becomes less effective and the performance of your vehicle becomes less efficient. A regular radiator flush (approximately once every 2 years) eliminates the build-up of sludge and rust. A vehicle's cooling system protects the automobile from the extreme heat generated by the engine and keeps the engine running within the proper temperature range. A regular radiator flushing should become a part of routine maintenance if you want to keep your vehicle operating at optimum levels.

Steps

1. 1
   Ensure the engine is completely cool. You will not be able to work otherwise. The engine is coolest when it has not been operated for at least two hours. This step is vitally important as coolant in a recently-used engine can be extremely hot and can cause injury if the coolant comes in contact with your skin.

   
   
2. 2
   Raise and fasten the automobile hood, locating the radiator which is usually located nearest you when you're at the front of the car. Clean the metal slats on the front and back of the radiator that allow air to move throughout (otherwise known as fins) with sudsy water and a nylon brush. Remove all dead bugs and debris from the radiator by brushing in the direction of the radiator fins (not against, as this may cause damage to the fins).
3. 3
   Center the drainage pan underneath the radiator's drain valve (otherwise known as a petcock). Drain the radiator by pulling the handle on the petcock. Make sure you are wearing your gloves for this step as radiator coolant is toxic. Once you have drained the coolant, put a lid on your drainage pan and set aside.
4. 4
   Ensure the existing parts that make the radiator work properly are in good working order.
   • The radiator cap acts as a lid for the radiator keeping it pressurized. It consists of a spring coil stretched between a wide flat metal top and a rubber seal. The tension between the seal and the spring is what allows the radiator to maintain the proper pressure. If any part is worn out, the cap may need to be replaced.
   • Two hoses run from the radiator, one that takes the heated coolant away and one that continually flushes the radiator with cold coolant. Ensure that these hoses are not cracking or that the clamps that hold them in place are not rusty. If either of these 2 conditions exist, they may need replaced as they are not allowing the coolant to flow as it should.
5. 5
   Rinse the radiator, once all of the old coolant has been drained, by placing a garden hose in the fill spout and running water into the radiator until it is full. Once full, remove the petcock and let the new water drain out.
6. 6
   Add new coolant. An ideal coolant consists of 50 percent water (distilled for best results) and 50 percent antifreeze. For best results, you should combine these 2 ingredients together before pouring into the radiator.
7. 7
   Bleed the radiator by leaving the cap off (to avoid pressure build-up) and starting the vehicle. Leave it running for 15 minutes to allow all air voids to exit the radiator. Once the coolant heats up, the air will exit the radiator and after all air is removed, there should be more room for coolant. Add any additional coolant at this time.

   
   

Tips

• Check for leaks once you have added new coolant. This can be done by removing drain pan from underneath the vehicle and checking for any coolant dripping from the radiator.

Warnings

• Radiator fluid has a sweet smell which attracts animals and children. Keep out of reach of both animals and children.
• Use a disposable pan for coolant drainage as fluid is toxic.

Things You'll Need

• 1 - 2 gallons (4 to 8 liters) Antifreeze
• 1 to 2 gallons (4 to 8 liters) Distilled water
• Drainage pan or bucket
• Garden hose with nozzle
• Work gloves
• Nylon brush
• Bucket of sudsy water
• Safety goggles

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