How to Flush a C5 Corvette Radiator

by David Curtis

The completely redesigned C5 model of the popular Chevrolet Corvette was manufactured between 1997 and 2004. The coolant drain plugs on the LS1 engine are not easily accessible so a system flush with clean water is recommended when changing the antifreeze. Take special care, when removing the radiator drain plug, as it is plastic and will break easily. Dex-cool antifreeze is available at any automotive parts supplier.

Park the car on a level surface and set the parking brake. Put on safety glasses and gloves for protection. Raise the front of the car with a hydraulic jack and position jack stands under it for safety. Remove the right front wheel with a lug wrench to gain easier access to the drain plug.

Open the hood and remove the radiator surge tank cap located next to the radiator for venting. Crawl under the right front side of the radiator and locate the drain plug. It will be facing the engine.

Place a drain pan large enough to hold 3 gallons of fluid under the drain plug. Twist the plug counterclockwise 1/4-turn with a socket wrench and carefully remove it. Allow the coolant to drain completely out of the radiator.

Replace the radiator plug and remove the container of used antifreeze. Dispose of the fluid properly.

Fill the radiator with clean water through the surge tank opening and replace the cap. Start the engine and warm it up until the temperature reads between 170 and 210 degrees on the driver's information display on the dashboard. This will flush clean water throughout the engine to remove the rest of the coolant.

Turn off the engine and remove the fill cap. Place the drain pan under the radiator again and remove the drain plug. Allow the flushed fluid to drain from the engine. Replace the plastic plug and dispose of the flushed fluid properly.

Open the surge tank cap and insert a funnel into the opening. Pour 6-1/2 quarts of Dex-cool into the system. Add distilled water until the fluid reaches the top neck area of the tank and replace the cap.

Start the engine. Increase the throttle until the tachometer reads 2000 RPM. Allow it to reach over 170 degrees to remove any remaining air in the system then shut off the engine. Open the cap and add enough distilled water to bring the level to 1/2-inch above the "Cold Full" tank mark. Replace the cap and wipe off any excess fluid from the radiator and tank area with a shop rag.

Drive the car for a week and check the coolant level again. Refill it if necessary.

Warning

  • close Only add Dex-cool at a mixture ratio of 50/50 with distilled water.

Items you will need

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  • photo_camera corvettes image by michael langley from Fotolia.com