How to Flush the Radiator in Chevrolet Carsby Contributing Writer; Updated June 12, 2017
Your vehicle's radiator can get clogged up with numerous contaminants over time. This is especially true for Chevy truck owners who travel in rough conditions. A clogged radiator on your Chevrolet car will cause major problems with keeping the engine cool, but you can solve this by flushing out the radiator. If the radiator cannot be flushed out using the following steps, you will need to have a service technician take a look at it.
Under The Hood:
- How to Flush the Radiator in a Chevy Cobalt
- How to Flush the Radiator in a Chevy Impala
- How to Flush the Radiator on the 2003 Chevy Impala LS
- How to Flush the Radiator in a Chevy Avalanche
- How to Flush a Radiator on a Chevy Tahoe
- How to Flush the Radiator in a Chevy Silverado
- How to Flush the Radiator in a 2000 Chevy Monte Carlo
- How to Flush the Radiator on a 2000 Chevrolet Silverado
- How do I Flush the Radiator in a 1999 Chevy Blazer?
Park the car on a level surface. To make flushing the radiator in a Chevy Cobalt easier, you may want park the auto on risers to elevate the front end of the Cobalt.
Open the hood and prop it up securely. Touch the radiator to make sure it is cool to the touch. A hot radiator can explode due to internal pressure and cause burn injuries.
Turn the radiator cap one turn to relieve any pressure. Allow a few seconds to pass, and then completely remove the radiator cap. Use waterproof work gloves to keep your hands clean and safe from injury.
Place a pan or bucket underneath the radiator drain valves located underneath the radiator. This pan or bucket should have a two-gallon capacity in order to hold the liquid.
Take a wrench and remove the radiator drain plug from the underside of the radiator.
Allow the radiator to drain completely. After completing the drain, place a cover on the bucket or pour the coolant into another sealable container. Coolant is very toxic. Take it to a local hazardous waste disposal company or to your local auto store for proper disposal.
Flush the radiator of the Chevy Cobalt out with distilled water. Tap water can leave sediments behind that can damage your coolant system. Allow the distilled water to drain into the pan and dispose of the flush solution. Repeat this process until the drained water is clear of debris.
Replace the radiator plug on the underside of the radiator.
Fill the radiator to the top with coolant recommended for the Chevy Cobalt. This coolant is available at your local Chevy dealer. The advantage to using this coolant is that it comes pre-mixed to the correct levels.
Start the auto and run it until the cooling fan turns on twice. Next, turn off the auto and check the level of the coolant. If the coolant level in the radiator retreats, refill the coolant until it is to the top of the radiator. Put the radiator cap back in place and close the hood.
Items you will need
Chevy Cobalt approved coolant
Pan or bucket
Park the Chevy Impala on a level surface. If possible, place the car on risers to make the underneath of the car more accessible. Be sure to set the parking brake before working on it.
Open the hood of the Impala and touch the radiator. If the radiator is cool to the touch, then loosen the radiator cap with one turn. Wait a few seconds to make sure the radiator pressure is gone. Now, remove the radiator cap.
Position a bucket or tray beneath the radiator drain plug to catch the old coolant. Be sure the tray or bucket has at least a 2-gallon capacity. Don't let coolant drain onto the driveway because it is extremely toxic to people and pets.
Use a wrench to remove the radiator drain plug from the underside of the radiator. In some models of the Impala, the drain is not directly underneath the radiator but on the backside of the radiator.
Allow the radiator to drain completely. After completing the drain, place a cover on the bucket or pour the coolant into another sealable container. Make certain you dispose of the coolant properly at the local liquid waste recycle center or automotive store.
Flush the radiator of the Chevy Impala out with distilled water. Tap water can leave sediments behind that can damage your coolant system. Allow the distilled water to drain into the pan and dispose of the flush solution. Repeat this process until the drained water is clear of debris.
Replace the radiator plug back into its original position.
Fill the radiator of the Chevy Impala to the top with the coolant that your owner's manual recommends. You may want to use the same type of coolant that was in the radiator previously because different types of radiator fluid will not mix well, even if only a small amount remains in the radiator.
Start the engine and allow it to run until the cooling fan turns on twice. Then turn the car off and allow the radiator to cool. Recheck the coolant level. If the coolant level went down, you will need to add more to the radiator.
Screw the radiator cap back into place and close the hood.
Items you will need
Pan or bucket
Park your Chevy Impala on a level surface. Wait for the radiator to cool down, then put on a pair of safety glasses and rubber gloves. You don't want used antifreeze to come into contact with your eyes or skin.
Place a drain pan beneath the drain valve on the radiator. Any deep pan will work, whether it is an oil pan, a kitchen pan, or even a dishpan.
Open the drain valve on the radiator and drain the used antifreeze coolant into the pan. While draining, open the hood of the Impala and remove the radiator cap by first pushing it down and then twisting it off.
Allow the radiator to drain fully, then close the drain valve. Pour the used radiator fluid into a funnel that drains into a regular two-liter bottle. Fill the bottle with fluid and cover it tightly. This and all the other drained radiator fluids must be taken to an automotive shop or hardware store for recycling.
Fill the radiator with water from a hose, then drain it again into the pan. Inspect the water for rust, sediment, dirt or debris. The drained water must be clear before you continue; continue to fill and drain until only clear water drains out.
Mix up an approximate 50/50 solution of new antifreeze and water in a five-gallon bucket. Use a half gallon of antifreeze to start, and mix in the same amount of water. Place the funnel in the radiator and pour the mix into the funnel. Completely fill the radiator with the mixture.
Start the engine and allow the radiator fluid to flow throughout the system. Run it for approximately 15 minutes, then shut it down and allow the engine to cool off. When the engine is cool, remove the radiator cover and top off both the radiator and the coolant overflow tank with the 50/50 mix.
Items you will need
Empty two-liter bottles with caps
Park the Chevy Avalanche on a level surface and set the parking brake. Be sure that the underneath of the car is easily accessible.
Open the hood and verify the outer temperature of the radiator. If it's not cool to the touch, wait until the temperature drops before you proceed.
Turn the radiator cap one full turn, pause for a few seconds to relieve any internal pressure and then remove the cap entirely.
Place a 2-gallon bucket or tray underneath the radiator and directly below the drain plug or petcock valve.
Loosen the drain plug to begin removing the old coolant. The drain plug on the Chevy Avalanche doesn't require any tools for removal. It should be on the back of the radiator a couple of inches from the radiator nipple.
Dispose of the old coolant in a sealable container, once you fully drain your radiator. Be sure to take the old coolant to a liquid water disposal site or your local auto repair shop, as this liquid is very toxic to pets and people.
Close the drain plug, fill the radiator with distilled water and then reopen the drain to flush the water. Repeat this process until the water runs debris-free into the drain container. You can use ordinary tap water, but it can leave sediment deposits behind, which can damage the radiator.
Make sure to tighten the drain plug on the radiator. Then, pour fresh coolant into the radiator until it is within an inch of overflowing from the top. You will need roughly 5 gallons of coolant to fill the radiator of a Chevy Avalanche.
Start the Chevy Avalanche's engine and allow it to run until the cooling fan turns on twice. Then, shut the engine off and check the coolant level. If it is lower than before, pour more coolant into the radiator. Put the cap on the freshly flushed radiator and close the hood.
Items you will need
Make sure the engine is cool. Wait at least three hours after last driving the vehicle or perform this maintenance before driving it at all on a particular day. Apply the truck's parking brake and block the front wheels.
Drain the engine coolant. Place a large, clean container under the radiator drain on the radiator's lower left side, pull out the rubber drain hose from its support, aim it into the container and open the drain fitting with pliers. Once the coolant is drained from the radiator, move the container to the engine block's drain plugs and remove the plugs to drain the remaining coolant.
Remove the thermostat from the engine. With the battery's negative cable disconnected, remove the air filter housing and intake duct, then find the thermostat at the engine front on the lower intake manifold. Detach the radiator hose from the thermostat housing by loosening its clamp, remove the cover's bolts/nuts with a wrench to remove the cover and remove the thermostat from the cover.
Reinstall the thermostat housing by itself, along with the hoses and plugs you drained the coolant from. Turn the vehicle's heating controls to "hot."
Disconnect the upper radiator hose and insert a garden hose into the opened inlet. Run the hose water through the radiator until clear water runs out of the radiator hose you just disconnected.
Reinstall the radiator hose and the thermostat, then turn the heater control to the maximum position. Refill the coolant surge tank with a 50/50 mixture of coolant and demineralized water, filling it to the tank's "fill cold" mark.
Start the Tahoe's engine with the coolant tank's cap still off and let the engine idle for about a minute. Put the cap back on without tightening it and run the engine up to 3,000 RPM every 30 seconds until it reaches its normal operating temperature.
Shut off the engine and remove the coolant tank cap. Restart the engine, let it idle for another minute and add more coolant to a half inch over the "fill cold" mark. Repeat the above-mentioned RPM cycles and shut the engine off after it reaches normal temperature. Refill the tank until it's a half-inch over the "fill cold" line again and securely close the cap.
Items you will need
Move the Chevy Silverado to a flat surface with as little incline as possible. If available, you can drive the truck onto risers to allow better access to the underneath of the vehicle. Be sure to set the parking brake before you start any work.
Open the hood of the truck and touch the radiator. If the radiator is not cool to the touch wait until it is. The contents of radiators can be under pressure and can explode, causing severe injury.
Twist the radiator cap one turn to allow any pressure inside to release. Wear gloves and a long-sleeved shirt to prevent injury to your skin. After the pressure releases, remove the radiator cap entirely.
Position a tray or bucket underneath the radiator plug on the underside of the Chevy Silverado's radiator. This container should have a volume of at least two gallons.
Use a wrench to remove the radiator plug and allow the contents of the radiator to drain into the container. After the draining completes, place the coolant in a sealable container for proper disposal. Because this coolant is toxic to pets and children, you don't want to dispose of it public areas.
Pour distilled water into the radiator to flush any remaining debris out of the radiator. Be sure that there is a bucket or tray to catch the flush water and continue flushing until the water is completely clear of debris. Avoid using tap water because any sediments from it can remain behind and damage your coolant system.
Place the radiator drain plug back into place underneath the radiator and fill the radiator with fresh coolant. Fill it all the way up to the neck of the radiator with an inch to spare.
Turn the ignition on and allow the car to run until the cooling fan turns on two separate times. Do this with the radiator cap still off the top of the radiator.
Check the coolant level and add additional coolant if the level retreated during the time the Chevy Silverado engine was active.
Put the radiator cap back on the radiator and close the hood. Perform any necessary clean up and proper disposal of any toxic coolant.
Items you will need
Bucket or tray for drainage
Distilled water (Approx. 2 gallons)
Park the Monte Carlo on solid level ground.
Open the hood and inspect the radiator and hoses. Replace damaged or leaky hoses right away. The front of the radiator may show a buildup of of dead insects and plant matter. Soak the radiator with the garden hose and scrub the debris off with the brush.
Allow the Monte Carlo's engine to cool completely, and then remove the radiator cap. Do not remove the radiator cap before the engine is completely cool. Serious injury can result.
Place the drain pan under the radiator below the drainage petcock.
Open the petcock and allow the coolant to drain until it stops flowing.
Insert the garden hose into the top of the radiator and allow water to flow through it until no more rust or old coolant drains from the radiator. You will need to stop occasionally to empty the drain pan.
Close the petcock and add fresh antifreeze and water in equal amounts until the radiator is full.
Replace the radiator cap and run the Monte Carlo's engine for several minutes. Allow the engine to cool and recheck the coolant level. Add additional coolant if necessary.
Dispose of the used coolant in a safe and legal manner.
Items you will need
5-gallon drain pan
Stiff bristle brush
Park the truck on a level surface, set the parking brake then place a large container under the radiator at the drain hose.
Disconnect the drain hose from its support and insert it into the container. Unscrew the radiator drain valve--use pliers if you can't do this by hand--and pour the engine coolant into the container.
Reconnect the lower hose and make sure the heating controls on the truck's dashboard are set to "Hot."
Loosen the clamp fastening the air duct to the air cleaner with a screwdriver and detach the air duct, then unscrew and remove the air cleaner housing with a screwdriver to access the thermostat.
Detach the radiator hose from the thermostat housing cover then unbolt and remove the cover with a wrench.
Remove the thermostat from the housing, taking note of the direction it is installed, then reconnect the empty housing to the engine block.
Disconnect the upper radiator hose at the radiator, loosening the hose clamp with a pair of pliers.
Insert a garden hose into the open fitting on the radiator. Turn on the faucet and look for water to come out of the disconnected radiator hose. Wait until clean water comes out of the hose.
Reconnect the hose to the radiator then reinstall the thermostat in its housing.
Reinstall the air filter housing and the air duct.
Refill the radiator. It is likely that the old coolant is contaminated so use a fresh mix of half water and half coolant.
Items you will need
Dex-Cool engine coolant
Locate Essential Components
Find the radiator cap inside the engine compartment. It is at the front and to the left, beside the battery. This cap maintains a constant pressure within the colling system and should never be opened while the engine is hot.
Locate the radiator drain cock. This device is at the bottom of the radiator, on the passenger side. It is a small cylinder that sticks out of the radiator toward the engine. It has a small fitting on the end that you unscrew to allow the coolant to flow. The coolant then travels out through a small tube attached to the drain cock to the bottom of the truck. If this tube is missing, replace it. The tube attaches to a small barb on the bottom of the coolant drain cock.
Look for the coolant reservoir behind the battery. It has a black plastic cap and may have a small amount of coolant inside. This portion of the system is not pressurized and can be opened at any time. This reservoir allows extra coolant inside the radiator to expand into it, and then the excess is automatically sucked back into the radiator as it cools.
Drain and Flush the Cooling System
Verify that the engine is completely cooled. Place a bucket under the plastic hose attached to the drain cock. Open the drain and allow all of the coolant to exit the radiator. This make take several minutes since the vehicle uses almost three gallons of fluid and the flow rate is very slow. Close the drain cock.
Pour the entire package of radiator detergent into the radiator through the radiator cap. Fill the rest with distilled water. When it is full, wait three minutes and add more water if the level has dropped. The level may drop due to water slowly flowing into other portions of the cooling system. Put the radiator cap back on and tighten.
Crank the truck. Let it run for 15 minutes. This allows the radiator detergent to loosen any deposits within the system. Keep an eye on the temperature gauge inside the truck. Temperature should not exceed 200 degrees F. If the truck begins to overheat, shut the engine off, allow it to cool and add more distilled water to the radiator.
Allow the engine to cool. Drain the water and detergent from the radiator into a bucket. Close the radiator drain cock after the flow stops.
Refill the system with distilled water through the radiator cap. Run the engine for 15 minutes, then let it cool. Drain this plain water into a bucket and close the drain cock. This step ensures that no residual coolant or detergent is left inside the cooling system.
Refill the Cooling System
Pour 1 1/2 gallons of high-quality antifreeze/coolant into the radiator. Fill the rest of the way with clean, distilled water. Adding the required amount of coolant first eliminates the need to mix the coolant and water to the required 50% solution and accounts for any water left in the cooling system. Be sure not to add pre-mixed coolant because this will throw off the required concentration.
Replace the radiator cap with a new one. These caps can fail without any outward evidence. A cap that is not maintaining the correct pressure can prevent the cooling system from operating and cause major engine damage. Tighten the cap and check all hoses and surrounding parts for wear. Replace any damaged parts.
Drain the coolant reservoir with a fluid vacuum. Catch all fluid in a bucket. Add a 50/50 mixture of coolant and distilled water to the "cool" line on the side of the reservoir. Put cap back on and tighten.
Check the coolant fluid level often after flushing the system. A good rule is to check one day, one week and one month after the service. Add distilled water when needed.
Discard all fluid from the flush according to local laws. Engine coolant is poisonous and sweet-tasting. Some automotive stores and local landfills have receptacles for disposal.
Items you will need
Coolant drain tube
2 gallons coolant
8 gallons distilled water
New radiator cap