Coolant Flush DIY

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May 24, 2006
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Hello, I was wonder if someone could post up a quick coolant flush DIY.

Really all i need to know is. Does my 99 accord have a drain valve on the bottom of the radiator? And is there anything else i need to know before i drain it and refill it... Thanks for any help.


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Sep 7, 2005
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Open your hood. Look straight down the radiator, you should see a white plug, that's the drain plug for your radiator.

If you have a Haynes it shows the proper way to flush your coolant.

But for ease....

Open that drain plug. Once that's drained, remove the lower radiator hose and allow the remaining fluid in the upper half of the engine block to drain. While its draining, remove the thermostat housing then reinstall w/ out the thermostat. This allows it to be fully flushed.

Reinstall lower radiator hose and tighten radiator drain plug. Turn heating knobs to hot so that the heater core will be flushed at the same time. Disconnect upper radiator hose, then place a garden hose in the upper radiator inlet and flush the system until the water runs clear at the upper radiator hose.

To refill - install thermostat, reconnect all radiator hoses. Keep heater control in hot position. Slowly fill the radiator w/ coolant until it reaches the filler neck. Then add coolant to the resevoir till it reaches the cold mark. Leave radiator cap off and run the engine in ventilated area until thermostat opens (upper radiator hose will become hot). Turn the engine off and let it cool. Add coolant to bring it back to the top of the filler neck of the radiator. Squeeze the upper radiator hose to expel air, add coolant if necessary, replace radiator cap. Place heater and fan controls on their max (hot, fastest) and start engine. Allow it to reach normal temp and check for leaks.
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