How to Flush a Coolant System on a 1989 Chevrolet Corvette

Flushing the cooling system of a 1989 Corvette is an integral part of keeping it on the road for years to come. Over time, contaminants can get into this system and cause major problems. The anti-freeze used in the system also acts as a lubricant for the water pump, and just as most lubricants, needs changing on occasion. Fortunately, the flushing process it relatively easy.

Tools Used: Garden hose, Coolant flushing chemical, 1-3/4 gallons of standard anti-freeze, 1-3/4 gallons of cool tap water, Drain pan, Phillips screwdriver, Safety glasses, Floor jack, Jack stands, Empty 4- to 5- gallon container

Flush a Coolant System

Open the Corvette's hood and remove the radiator cap. Pour the flushing chemical in the radiator, as directed by the instructions on the chemical, and close the radiator cap. Start the vehicle and allow it to run for the time suggested by the instructions on the chemical, typically 10 to 15 minutes. This allows the chemical to loosen any debris deep in the cooling system and make it settle at the bottom of the radiator, keep a close eye on the vehicle's temperature gauge, and shut it down if overheating occurs.

Allow the vehicle to cool until the radiator is cool to the touch and remove the radiator cap slowly. Raise the front of the vehicle with the floor jack and place the jack stands beneath the Corvette to secure it.

Place the drain pan directly beneath the lower radiator hose, the rubber hose inserted in the bottom of the radiator. Put the safety glasses on, crawl beneath the vehicle. Remove the lower radiator hose by loosening the metal hose clamp with the screw driver and pulling the hose from the radiator. Be prepared for a quick flow of coolant from the radiator into the drain pan. Never drain the coolant through the drain plug during a flush, as the loosened debris can get stuck in the drain creating additional work.

Dump the old coolant from the drain pan into the 4- to 5-gallon empty container for recycling. Most auto parts stores will take old coolant for recycling. Place the drain pan back under the vehicle.

Place the garden hose into the opening at the top of the radiator and turn the water to the hose on. Observe as debris begins to be forced out by the water. Continue this step until only clean water flows from the radiator. The drain pan and 4- to 5-gallon container may need to be emptied several times during this process, depending on the amount of debris in the radiator.

Place the lower radiator hose back on the radiator and tighten the metal hose clamp, using the Phillips screwdriver.

Remove the jack stands from under the vehicle and lower it, slowly, to the ground.

Fill the radiator with one gallon of anti-freeze, then start the vehicle. Fill the empty 1-gallon anti-freeze container with cool tap water. Notice the coolant level will drop as the vehicle warms up, add anti-freeze each time it drops until you reach a total of approximately 1-3/4 gallons of anti-freeze. Add cool tap water until the radiator is full at proper operating temperature. Close the radiator cap.

Check the coolant level in the coolant reservoir bottle, the plastic bottle connected to the radiator by a thin rubber hose, and make certain the coolant level is between the "Min" and "Max" lines on the reservoir. Add a 50/50 mix of antifreeze and cool tap water if the level is not correct.

Close the Corvette's hood and allow it to run for 10 to 15 minutes, with constant monitoring of the temperature gauge.

Tips & Warnings

Always dispose of used anti-freeze properly, it is highly toxic to children and small animals.

Though some Chevrolet vehicles use Dex-Cool anti-freeze, the 1989 Corvette is not one. The use Dex-Cool can lead to cooling system failure.

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