Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

How to burp out the air when changing engine coolant

strong text on my 2003 Buick Lesabre custom I want to drain and flush then refill the cooling system with Dexcool and distilled water. now on my other cars even with bleeder screws I do not like to open those little screws that can easily snap off I done that been there, so can I burp the air out without touching those little hard to get at bleeder screws , can I squeeze the top and bottom radiator hoses to get the air out then run the engine recheck the fluid level and add to it .strong text


Draining and filling with the solution you have chosen is a good idea (provided that you currently have Dexcool in the system).

I’d have more concerns with opening the plastic drain valve that with opening the bleeder screw. These cars can be challenging, in regards to draining, because of the location of the drain and the fact that everything is plastic. Are you using a coolant flush tee kit?

I’ve done coolant several of these engines. You should not have a problem opening and closing the bleeder screw. Remove the oil filler pipe (with cap on it) by turning counterclockwise a little until it stops and pulling straight up. then the sight shield (plastic engine cover) will lift off (there’s a little tab in back that fits loosely in a bracket).

Where the upper radiator hose meets the thermostat housing, you’ll see the bleeder screw (small - I think about 7mm wrench - and BRASS). I’ve never had a problem unscrewing one from its brass fitting. Just loosen it a couple turns. When tightening it. be very gentle as the needle valve is brass and just need to be “snug” or you risk stripping threads or damaging the needle.

While it’s loose. fill the radiator letting the coolant settle and keep adding until it stops going down and the radiator stays full. Run the engine for 3 minutes and refill radiator as needed.

Before filling the system I always remove and clean the reservoir, reinstall and refill at least to the “full hot” line. Keep checking coolant level and adding after each of 3 complete engine cold-to-operating temperature-to cold cycles.

1 Like

as for the drain Ill try to loosen it first with the ears on it .sounds great except those bleeder screws, cant I just fill with dex cool and squeeze the lower then upper radiator hose to release the air then follow up with the rest of the instructions?

When the engine doesn’t have a bleeder screw for the cooling system, or a radiator cap for that matter, I purge the air from the cooling system using this method.

Start the engine and let it idle until it comes up to operating temperature.

While the engine is idling, loosen the upper radiator hose clamp and slip a small flat bladed screwdriver in between the radiator hose and hose neck on the radiator.

Allow the engine to continue to idle until all the air is purged from the cooling system and where nothing but coolant comes out.

Remove the screwdriver and reinstall the hose clamp.

I’ve used this method for over 40 years, and it works every time.


THANK YOU FOR YOUR MOST LOGICAL ANSWER ,those caps. well any way Im still learning , all advice is good.

good idea I thought I knew all the tricks however still learning:kissing:

No experience with your engine configuration, but I did remove a stubborn brass screw from a carburetor recently. Might work for you too, who knows? Might be worth a try anyway. I cooled the brass screw by holding a piece of ice against it for a couple minutes, the idea is the temperature change will make it shrink a little. It worked, came unstuck straight away.

1 Like

Thanks for the ice cooling trick ,every bit counts when your dealing with a stuck threaded device.

The coolant reservoir is a good means to burp the air out of the system. One can either buy another radiator cap that is several pounds under the factor one or remove the rubber seal on the underside of the radiator cap being used. If the cap is one with the new reduced pressure, drive the car, normally, on residential streets. After the car reaches its normal operating temperature, take it home or somewhere to let it cool (Errands, etc) You’ll need 2-3 more of these jaunts,Take some water with you if for some reason that it is needed. The driving and cooling will burp the system. A real rise in temperature should not be a problem .However, high outside temperature will effect this cap’s ability to control the radiator’s cooling. Put the original cap back on when done. If the original cap is used where the rubber seal is temporarily removed, keep the vehicle hood up watching that there is no more than some spillage from around the radiator neck at the most, Run the motor 3-4 minutes after it reaches operating temperature, Turn the motor off for about 15-20 minutes, longer if the outside temp is high. Do this another 3-4 more times. Put the removed rubber gasket back on and install cap. Before starting any of this make sure the coolant reservoir is at the “cold” mark when the motor is actually cold.

Thankyou every bit helps. I did basically what you recommended without moving the car however I squeezed the upper and lower hoses to burp it with the cap off and hot running you could see the air come out of the cap , then I increased the rpm a few times by pushing the gas pedal , then put the cap on and making sure the overflow was a little over the full hot line and it worked for me. thank you .:grin:

Good for you. Thanks for posting your good result.

1 Like

very good idea because that’s the highest point oh the antifreeze