How to Bleed the Cooling System on Vehicles

by Contributing Writer; Updated June 12, 2017

The cooling system in the Vehicles engine can collect air pockets when certain parts of the cooling system are replaced, such as the water pump, thermostat, or radiator hoses. Coolant that falls out of these parts does not automatically get replaced with coolant when you reinstall them. The cooling system breathing process is one of heating the system without pressurizing the system. The heated cooling system will force the air pockets to the top and out of the cooling system, as the air pockets weigh less than the coolant.

Under The Hood:

 How to Bleed the Cooling System on an Audi 1.8T

Raise your Audi's front end by placing a floor jack underneath the jack points that are located directly behind each of the front wheels.

As each corner of the front end is raised into the air, place a jack stand underneath the jack point and lower the car so that it is supported on the jack stand.

Locate the drain plug that is positioned directly behind the radiator at its bottom end.

Position a drain bucket below the drain plug.

Grasp the latch at the middle of the coolant drain plug and twist it in either direction as you pull it down to remove it.

Allow the coolant to drain out of the drain plug and into the drain bucket. Replace the drain plug when the coolant has finished draining.

Open the coolant expansion tank located on the driver's side of the engine bay near the windshield's end of the engine bay.

Pour the replacement coolant into the expansion tank and replace the expansion tank's cap once you have completed the task.

Items you will need

  • Drain bucket

  • Floor jack

  • Jack stands

  • Coolant

 How to Bleed the Cooling System on a Pontiac Sunfire 2.2L

Open the hood on your Sunfire. Remove the radiator cap from the radiator overflow bottle.

Turn the engine on in the Sunfire, and let the engine run for no less than 15 minutes. Set the dials on the heater control panel to full fan speed, full heat, and front defrost positions. This will speed up the processes of heating the engine to full temperature. Removing the radiator cap and performing these procedures will allow the pressure in the engine to build up. As the pressure gradually increases, the weight of the coolant will force air bubbles out through the radiator overflow bottle hole. This process is called bleeding the cooling system.

Turn the engine off when you notice that there are no more bubbles coming from the radiator overflow. Top off the radiator overflow bottle with fresh coolant. Use 50/50 diluted, universal coolant to fill the overflow. Replace the radiator cap when the reservoir is at the "Full" mark.

Items you will need

  • 1 gallon 50/50 diluted, universal coolant

 How to Bleed the Cooling System in a 1999 Taurus

Raise the hood of your Taurus. Carefully inspect the radiator hoses for signs of leaking. These will show up as white or rust colored areas around the hose ends. Fix any leaks before you continue.

Be certain that the engine is cool, and remove the expansion tank cap.

Turn the heater on and place the switch in the maximum setting.

Start the engine. Leave the expansion tank cap off. Allow it to run until the upper radiator hose becomes hot. This indicates that the thermostat has opened.

Turn the engine off and allow it to cool. Add coolant, if necessary to bring the level up to the "Full Hot" line on the tank. Using your hands, squeeze the upper radiator hose. This pushes air out of the system.

Replace the expansion tank cap and start the engine. Allow it to reach operating temperature and check the coolant level again. Adjust as necessary.

 How to Bleed the Cooling System on a Chevy Cavalier

Start at the furthest point of the actual cooling system supply. For any car, this would generally be at the heater core. This is usually under the dashboard at the place where the hoses hook together and come through the firewall.

Locate the two hoses going through the firewall into the heater core.

Disconnect one of these with a screwdriver.

Have someone else start the engine. Make sure the loose end of the hose is pointed towards the ground

Make sure the heater is on. Turn it on at the dashboard, just like you would in the wintertime.

Wait for water to start circulating and it will push the air out of the loose hose.

Put the loose hose back on the heater connection once water starts running out to keep any air from reentering the system. Just push it back onto the heater connection where you removed it. Have someone turn the car off and re-tighten the screws.

Items you will need

  • Screwdriver

  • Pliers

 How to Bleed a Coolant System on a 2001 Dodge Stratus

Find the coolant bleeder valve, a 1/4-inch metal valve attached to the engine block directly under the upper radiator hose. Press a 4-foot-long, 1/4-inch-inside-diameter clear plastic hose onto the bleeder valve. Route the hose down the front of the engine and into a drain pan.

Open the bleeder valve by turning it one turn counterclockwise with a combination wrench.

Unscrew the cooling system pressure cap -- the cap on the end of the upper radiator hose -- and remove it.

Add 50-50 premixed green ethylene-glycol-based coolant through the filler neck where the pressure cap was installed until you see coolant flowing from the clear plastic hose and into the drain pan.

Close the bleeder valve by tightening it with a combination wrench and pull the clear, plastic hose from it. Continue adding 50-50 premixed coolant until the level reaches the base of the filler neck. Tighten the pressure cap onto the filler neck.

Open the coolant recovery tank and add 50-50 premixed coolant to the tank until the coolant level reaches the “Max” mark on the tank.

Start the engine and allow it to idle until you hear the cooling fans turn on, then shut off the engine. Allow the engine to cool until it feels cool to the touch, then recheck the coolant level in the coolant recovery tank. Add more coolant to the tank as needed. The 2.4-liter engine has a total capacity of 1.85 gallons, but the amount needed to refill it may vary.

Items you will need

  • Clear plastic hose, 4 feet long with 1/4-inch inside diameter

  • Drain pan

  • Combination wrench set

  • 2 gallons of 50-50 premixed ethylene-glycol-based (green) coolant

 How to Bleed the Coolant System in a 1999 Oldsmobile Silhouette

Allow the engine to cool for no less than 2 hours if you have recently driven the van. Raise the hood on the Silhouette and set the hood prop, after the engine has cooled. Visually inspect the top of the radiator to locate the radiator cap.

Place a drain pan under the car, directly beneath the radiator cap area. Open the radiator cap if it is cool to the touch. If the radiator cap is hot or very warm, allow the van to cool for at least 1 more hour. Remove the cap only when the cap is lukewarm or cool to the touch.

Install a pair of locking pliers or a radiator hose-hand clamp onto the upper radiator hose, on the driver's side of the engine. Squeeze the hose completely shut. Add engine coolant to the radiator until it is nearly full. Leave the radiator cap off at this time.

Turn the engine on and let the engine run for no less than 15 to 20 minutes. Turn the heater control switches to full heat, defrost mode and full fan speed. Turn the rear heater on at full fan speed and full heat, if equipped.

Check the coolant level frequently, and add coolant when you can begin to see the silver fins inside the radiator. Continue adding coolant until the radiator stays full, and there are no more signs of air pockets. Assuming your van engine is running at a smooth idle, the coolant level in the radiator should stay steady. A rough idle will cause the level to go up and down with the speed of the water pump. Allow the engine to run for 5 minutes beyond the point where you see the last air bubble.

Remove the upper pliers or clamp from the upper radiator hose, with the engine still running. Fill the radiator until it is completely full. Allow the engine to run for approximately 5 more minutes after your final radiator filling.

Shut the engine off, then install the radiator cap. Make sure the cap is tightened to the second notch or rotation. The first 90 degrees a radiator cap is turned is a vent release position. The second 90-degrees locks the cap down completely. Add coolant to the radiator overflow reservoir. Read the reservoir caps carefully so as not to add coolant to your wiper fluid reservoir.

Items you will need

  • Drain pan

  • 1 to 2 gallons 50/50 universal coolant

  • Flat-nose locking pliers or radiator hand-hose clamp

 How to Bleed a Coolant System on 1996 Chevrolet Impala

Draining

Park the Impala on firm, level ground. Place the transmission in "Park" and set the parking brake. Open the hood and allow the engine to cool until the radiator cap is cold to the touch.

Wipe the coolant reservoir cap with a clean shop rag to remove debris that may fall into the reservoir. Remove the cap from the reservoir. Find the radiator drain petcock on the rear of the radiator, at the bottom driver-side corner. Place a catch pan below the petcock and open it by hand. Allow the radiator to drain fully. Close the petcock

Locate the air-bleed valve on the water-pump inlet just above the water pump on the front of the engine. Place a clean shop rag between the air-bleed valve and distributor to prevent fluid from contaminating the distributor. Open the air-bleed valve, using a wrench.

Find the knock sensors in the middle of the engine block on both sides. Disconnect the electrical leads. Slide the catch pan beneath the each knock sensor in turn, and then remove the sensors, using a ratchet and socket. Allow the coolant to drain fully from the engine water jacket in the block.

Filling

Install the knock sensors and torque them to 14 foot-pounds, using a foot-pound torque wrench and socket.

Add a 50-50 blend of coolant and distilled water to the coolant reservoir. Observe the coolant leaving the air-bleed valve, and close the valve once air bubbles are no longer apparent in the reservoir. Close the valve, using a wrench.

Start the engine and allow it to idle with the reservoir cap off until the thermostat opens. Open the air-bleed valve, using a wrench, and observe the coolant stream. Close the valve once the coolant stream is free of air bubbles.

Add two coolant supplement sealer pellets to the coolant reservoir. Fill the reservoir until the level is approximately one inch above the "Full Cold" mark. Install the reservoir cap and allow the engine to reach full operating temperature. Check for leaks.

Items you will need

  • Clean shop rags

  • Catch pan

  • Wrench set

  • Ratchet

  • Socket set

  • Foot-pound torque wrench

  • 15.1 quarts Dexcool Orange coolant or equivalent

  • Two coolant supplement sealer pellets, part No. 3634621 or equivalent

 How to Bleed the Coolant System on a PT Cruiser

Filling the Cooling System

Open the coolant system bleeder valve located below the radiator pressure cap using a wrench.

Install a clear, 4-foot long, 1/4-inch inside-diameter hose on the bleeder valve nipple. Route the hose down through the engine compartment and away from the radiator fan and accessory drive belts. Place the loose end of the hose into a clean container.

Remove the radiator pressure cap. Install the filling-aid funnel on the radiator pressure cap neck. Pinch the overflow hose using the attached clip.

Slowly add a 50 percent mix of coolant and distilled water to the larger section of the filling-aid funnel until a steady stream of coolant comes through the bleeder valve. Tighten the bleeder valve using a wrench and then remove the hose.

Remove the clip from the overflow hose and remove the funnel from the pressure cap neck.

Fill the radiator up to the top of the pressure cap neck. Install the pressure cap.

Fill the coolant overflow bottle to the “Full Hot” mark.

Bleeding the System

Start the engine and allow the vehicle to achieve full operating temperature.

Shut the engine off and allow it to cool completely.

Check the coolant level in the overflow bottle and add coolant up to the “Full Hot” mark.

Perform Steps 1 through 3 until the coolant level stabilizes at the “Full Hot” mark and no more coolant needs to be added. This may take three or four cycles.

Items you will need

  • Wrench set

  • 1/4-inch inside-diameter clear hose, 4-feet long

  • Clean container

  • Chrysler special tool 8195 filling-aid funnel

  • Mopar Antifreeze and Coolant, 5-year/100,000 Mile Formula or equivalent

  • Distilled water

About the Author

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