Flush a Radiator

A functioning radiator is essential to keep your car from overheating. Liquid coolant, heated by the engine, is funneled through the radiator, where it is cooled by heat exchange. Over time, sludge builds up inside the radiator and the coolant becomes less effective, which will hurt your engine performance and gas mileage. Flushing your radiator regularly, usually once every two to five years, will keep you car running smoothly.

Steps

  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 it comes in contact with your skin.
  2. Jack up the front of the car. While not strictly necessary, raising the front of you car makes it easier to work underneath the radiator and helps eliminate air bubbles from your coolant when you flush the radiator.[1]
  3. Raise the hood and locate the radiator. The radiator is usually near the front of the car next to the engine. Clean the metal slats on the front and back of the radiator that allow air to move throughout (otherwise known as fins) with soapy water and a nylon brush. Brush in the direction of the radiator fins to remove dirt and grim (not against -- this may cause damage the fins).[2]
    • It may not be possible to clean the slats, as the A/C condenser is sometimes mounted in front of the radiator, blocking the slats.
  4. Ensure the existing radiator works properly and is in good working order. Look for large patches of rust, corrosion, or leaky pipes and hoses. If, for example, you can smell antifreeze while driving, you may need to take you car in for a larger fix than simply flushing.[3]
    • 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. The top hose is where hot coolant enters the radiator, and the lower hose is where cooled coolant enters the engine via the coolant pump. Ensure that neither hose is collapsed, as this will prevent coolant from flowing properly.
  5. Center a drainage pan underneath the radiator's drainage valve, or petcock. Petcock's come in various shapes and sizes, but they are all small plugs that you can pull out to drain away fluid. Put a pan underneath the petcock to catch all of the fluid when you drain it.
    • The petcock is usually attached to the bottom of one of the radiator tanks and is the only bolt you will find there.
    • You may need to remove a small plastic covering from beneath the radiator to get to the drainage valve. This can be done with a screwdriver.[4]
  6. Drain the radiator by pulling out the petcock. Make sure you are wearing work 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.
    • Take your fluid to a nearby mechanic to be recycled.[5]
  7. Flush the radiator with water. Draining your radiator will only remove above 40-50% of your old coolant[1], so you need to flush it with water to get the rest out. To do so:
    • Replace the petcock in the radiator.
    • Place a garden hose in the fill spout and fill it until you see the water line.
    • Start the car and leave it on for 10 minutes. Let the car cool before returning to it.
    • Remove the petcock and let the new water drain out into a pan. This water will be tainted by the toxic coolant still in the radiator, so it must be recycled as well. Do not allow this water to drain into the ground.
    • Repeat this process 2-3 times.[3]
    • You can also buy "radiator flush cleaning solutions" to add with the water for a cleaner radiator. Make sure you drain all of the solution before refilling with coolant.[6]
  8. Add new coolant up to the fill line. An ideal coolant consists of 50% distilled water and 50% antifreeze. Combine the two ingredients together in a large bucket before pouring them into the radiator. Make sure you buy the appropriate coolant for your car.
    • Check your owner's manual for coolant suggestions, or bring your car's make, model, and year information to your local auto shop for advice. Be sure to note how much coolant you need -- this can range from 6-18 quarts.
    • Most cars use green coolant, but Toyota cars specifically need red. Orange coolant is newer and supposedly has a longer lifespan, but it is best to use the same coolant each time you change it.[1]
    • Mixing coolants can cause coagulation of the coolant, leading to costly repairs.
  9. Bleed the radiator of any air pockets. Take off the radiator cap to allow the air to escape, then turn the car on. Leave it running for 15 minutes with the heater turned on, allowing all air voids to exit the radiator. This will make more room for coolant, so be sure to add more coolant up to the fill line again.



Tips

  • When performing a coolant service, it is a good time to replace the thermostat, radiator cap and hoses on older vehicles.
  • Take the old coolant to your local auto store or hazardous household waste disposal sites for recycling, because spills can be toxic and fatal to animals.
  • 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.
  • There are certain additives that might be necessary to add to the cooling system when dealing with diesel engines and aluminum engines, refer to maintenance manual.

Warnings

  • Radiator fluid has a sweet smell which attracts animals and children, but is incredibly toxic. Keep out of reach of both animals and children.
  • Use a disposable pan for coolant drainage, and label all fluid correctly.

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

Related Articles

Sources and Citations

  1. ↑ 1.0 1.1 1.2 http://www.popularmechanics.com/cars/how-to/a78/1272246/
  2. ↑ http://www.ehow.com/facts_7591888_car-radiator-located.html
  3. ↑ 3.0 3.1 http://partsource.ca/do-it-yourself/how-to-radiator-coolant-flush
  4. ↑ http://www.doityourself.com/stry/what-is-a-radiator-drain-petcock
  5. ↑ http://www.earth911.com/recycling-guide/how-to-recycle-automotive-fluids/
  6. ↑ http://autorepair.about.com/od/regularmaintenance/ss/coolant_flush_3.htm#step-heading
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