How To Bleed Your Radiator

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Bleeding a Car’s Radiator

  1. Look for symptoms that your car’s radiator isn’t working.A car’s radiator needs bleeding for the same reason that a home’s radiator does – pockets of air have become trapped in the car’s cooling system. This prevents antifreeze from circulating effectively, causing the car to overheat. If you observe one or more of the following symptoms, your car’s radiator may need bleeding:
    • Abnormally high temperature readings on your dashboard temperature meter.
    • Fluid boiling out of your radiator.
    • Odd smells from your engine, especially sweet smells (caused by antifreeze leaking and/or burning up.)
    • Additionally, it can be a good idea to bleed your radiator after performing maintenance or part replacement on your cooling system. Air can be introduced to the system during maintenance work – keep an eye on your temperature gauge after modifying your cooling system in any way.
  2. Locate and loosen your car’s bleeder valve.Some cars have bleeder valves incorporated into the cooling system which function by releasing trapped air, just like the bleeder valves on a home radiator. Consult your owner’s manual to find the precise location of this valve – usually it’s located at your cooling system’s highest point to most effectively release air, which naturally rises.
    • To bleed a car’s radiator via a bleeder valve, simply loosen it until you hear the hissing sound of air escaping. Use a cloth to catch any sputtering coolant, then re-tighten the valve when the valve releases a steady stream of coolant.
    • Some cars don’thave special bleeder valves. Don’t worry – it’s still possible to bleed these cars’ radiators via other processes (see below.)
  3. Start the car with the radiator cap off. Another easy way to bleed the car’s radiator is simply to allow it to idle with the radiator cap removed (this is also a great option if your car doesn’t come equipped with a special bleeder valve.) Remove the radiator cap, then allow your car to run for about fifteen to twenty minutes. The air pockets should be forced through the cooling system and bubble out of the car’s radiator.
  4. Elevate your car. Air naturally rises, so by raising the front of your car, putting the radiator at a higher point than the rest of your cooling system, you can speed the release of air from your system. Carefully use a jack to raise your car – most cars come with one, but if yours didn’t, they’re available at auto supply stores. Ensure your radiator cap is loosened or removed beforelifting the car.
    • In certain special car varieties, the radiator may not be located at the front of the car – consult your car’s owner’s manual if you’re not sure.
  5. Perform a “flush and fill.” After you’ve bled a car’s radiator, it can be a good idea to add new coolant. Trapped air can artificially inflate a car’s coolant reading – you may be running low on coolant without having realized it. Drain old coolant from your system and add fresh coolant, observing any special instruction in your owner’s manual. Below are general instructions for replacing your car’s coolant:
    • Allow the engine to cool completely.
    • Place a drainage pan under your radiator’s drain valve to collect old coolant.
    • Add water to the car’s radiator until it’s full, then allow it to drain out of the drain valve under the car.
    • Close the drain valve and add fresh coolant, generally a 50/50 mix of antifreeze and distilled water (not tap water, which can form mineral deposits.)
    • Bleed your radiator again to eliminate any air introduced during the flush and fill.

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