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By maintaining your car’s cooling system, you can prevent roadside emergencies and extend the life of your engine. An important part of cooling system maintenance is a regular radiator flush. This will help the engine coolant circulate throughout the system and prevent potentially serious problems down the road with corrosion – most notably heater core or head gasket leaks. The following steps will guide you through the process of flushing your radiator.

Choosing the Right Coolant

You can find information pertaining to the type of coolant and the exact amount you should use by reading the owner’s manual for your vehicle. Also, check out these blogs on everything you need to know about engine coolant. You can consult with an AutoZone store associate for guidance if you have further questions.

Prioritize Safety

Your first priority when learning how to flush a coolant system, or completing any vehicle maintenance project, is your personal safety. Start by parking your car on a surface that is both dry and flat. You can then use wheel chocks so that your vehicle will not move while you’re working.

Wait for at least an hour after you turn off your engine before attempting to flush your radiator. Place your hand near the car radiator to get an idea of the car’s heat level. If you feel no heat, place your hand near the radiator cap. Again, if you feel no heat you can proceed with the job. Finally, safety gloves and goggles should be worn while doing this job.

Tools and Equipment

Flushing your car’s coolant system is more than just emptying the radiator and refilling, as the car’s engine block, heater core, and other items all contain antifreeze. DIY flush kits are available at AutoZone that hook into your heater hoses and flush garden hose water through the entire system, and through your heater core.

It is highly recommended that when doing a flush, you are flushing the entire system out with water in this fashion. Once you’ve determined whether you are going to do a complete flush or just a radiator drain/full, proceed by opening your hood and secure it so that you can inspect your radiator along with all the attached hoses. Keep an eye out for any leaks, cracks, or stressed-looking rubber. A worn and damaged hose may need to be replaced. At this time, install your flush kit into the heater hose if you plan on flushing the system.

How to Flush Your Radiator / Cooling System

1

Safety First

Park your vehicle on a flat, dry surface and install wheel chocks. Make sure the vehicle has not been running for at least an hour and that the engine and radiator are cool. Be sure to wear safety goggles and protective gloves. Keep coolant away from pets or small children. Clean up any spills immediately. Do not pour coolant down a drain or toilet.

2

Setting Up The Job

Open and secure the hood. Inspect the radiator and hoses for any cracks or signs of leaks. Once you’ve determined whether you are going to do a complete flush or just a radiator drain/full, proceed by opening your hood and secure it so that you can inspect your radiator along with all the attached hoses.

Keep an eye out for any leaks, cracks, or stressed-looking rubber. A worn and damaged hose may need to be replaced. At this time, install your flush kit into the heater hose if you plan on flushing the system. If you notice a worn or damaged hose, it may need to be replaced.

3

Press Down and Remove the Radiator Cap

Carefully press down on the radiator cap and remove it. Make sure the vehicle has not been running for at least an hour and that the engine and radiator are cool. Opening the cap on a hot radiator is extremely dangerous.

4

Locate the Drain Plug and Loosen

Locate the drain plug. This is found on the bottom of the radiator. Place a pan under the drain plug to catch old coolant. Loosen the drain plug and allow coolant to flow. Tighten the drain plug when coolant has stopped flowing.

5

Fill the Cooling System with Distilled Water

Check instructions on flush bottle for specific steps. Steps vary according to flush product. Fill the system with both water and flush product. Using a flush product is good to break up any sediment or corrosion and get it out of the system.

6

Install the Radiator Cap and Run the Engine

Install the radiator cap and run the engine for 10 minutes with the heater on maximum. Only run the engine outdoors or in a well-ventilated area. Turn off engine and allow radiator to cool. Repeat drain procedure.

7

Loosen Lower Radiator Hose

Once you’ve ran flush through and drained the radiator again, it’s a good idea to get any sediment out of the bottom of the radiator that the drain cannot remove. Once the hose is loose and can be removed. Fill the radiator up with garden hose or bottled water, then pull the hose and drain any sediment / dirty water out. At this point, very little of the water will contain antifreeze, but a good deal of sediment that has settled in the bottom of the radiator will come out. Next, hook up your hose to your flush valve you installed and follow the flushing instructions.

8

Drain Out Final Dirty Water

Once the system has been completely flushed, you will need to drain the system of the remaining dirty flush water in both the radiator, and as much out of the block as you can. Remember, all of this water contains antifreeze, so make sure you follow local ordinances on capturing antifreeze.

9

Fill with New Antifreeze

Fill the system with new antifreeze. If using concentrated antifreeze, be sure to use distilled water. Located any bleeder screws in the system that need to be opened to remove excess air. It is vitally important that these are located, or an air bubble can cause the car to overheat.

The Cleanup

Clean the area around your pan and make sure no spilled fluids are on the ground. Next, you need to dispose of the old coolant and other fluids in your pan. There are many laws governing the disposal of these fluids and they vary in different jurisdictions, so make sure you are following the regulations where you live. Whatever you do, never pour these fluids down your toilet or into a drain. Finally, give yourself a hand. You now know how to flush your radiator and cooling system!

Get the Help You Need

Both draining and replacing the coolant in your engine are repair jobs that will present a moderate level of difficulty. If you have any questions about the coolant flush cost or any step in the flush process, don’t hesitate to call or visit your nearest AutoZone store. Also, most automotive shops are equipped to quickly and safely flush the car’s coolant system – check any of these preferred installers in your area who can flush your car’s coolant system.

Advice, how-to guides, and car care information featured on AutoZone.com and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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