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Possible air in the system after radiator flush? I need your advice anyone?

Hello everyone in the car world I own a 2002 mustang v6 . 2 days ago I did a coolant change, when I was filling the radiator and reservoir with coolant I made sure to avoid having air bubbles in the system by having the car running without the radiator cap off and having the car’s front end raised up and the bleeder valve off. I also squeeze the hoses as I filled it up. Now here’s my question when do you know when your radiator is actually full? ???Cause the day after some drives I had to fill the radiator just a tiny bit more And I made sure the bubbles were gone after each time I had to fill it up. Next day I checked again and I still had to fill it up just a tiny lil bit to get it to the rim and Trust me I checked everywhere for any leaks and I found none is it possible there still be air in the system?? After seeing no more bubbles I thought it was all good My car doesn’t overheat, the heater works the upper hose feels hot and lower hose feels a little warm same with radiator after a drive and I know the thermostat opens and closes the cap looks like in good condition, what could it be?

There will always be a small amount trapped after the first fill, but not much. If you are just adding a tiny bit you probably have got all the air out. And with everything showing normal you can call this a success.


Glad to hear that’s normal, Thank you Stevecbt

My cars won’t keep the radiator clear full either, and nothing is wrong.

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As long as the car is running normal you should be okay . The cooling system is a mysterious thing lol

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The only thing I might recommend is trying another bleeding procedure. First, you start the car on a flat surface and let it idle for 5-10 minutes, until it gets nice and warm. Then you pop the throttle two or three times and shut it off. Then, after it cools down, you remove the radiator cap and top off the radiator. Repeating this two or three times might help you remove any remaining air in the system.

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Check in in a day or so, and then a couple days after that if all is good the first time.

It’s not uncommon for air bubbles to get trapped and work their way out after a couple of drive cycles.

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If your car uses a valve in the cooling system to control coolant flow to the heater core, setting the heater temp control to High opens that valve and lets old coolant out and new coolant in to the heater core. The heater setting could be a factor in having a problem-free coolant replacement.

Some cars have that valve, controlled by the heater temp control in the cockpit. Others use doors that open and close around the heater core, which has full flow of coolant all the time.

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I normally over-fill by 8 to 12 ounces, road test, cool for 30 minutes and check the level again. There is no time to count the bubbles in the repair industry.

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