Airbubbles in radiator, normal or should I worry?

twilightcall · 06-09-2003, 04:08 PM

I checked the coolant level in my car today. It was a little low so I topped it off. I started the car and left the cap off. Once it was start I saw a bunch of small air bubbles come up through the coolant and the level went down a little. After about 10-20 secs. the air bubbles stopped and the coolant gradually rose back up. After that I saw no more air bubbles. I checked my oil and there was no coolant in the oil. Is this normal or is this a sign of a headgasket issue? How do you bleed air out of this system? I didn't see a bleed screw on the rad. or on top of the therm. housing. Thanks for the help.

mustangII460 · 06-09-2003, 04:24 PM

You didn't post what year car or motor etc.

Low in the recovery tank? Or just in the Radiator? Some coolant will get pushed out/burned off. A few bubbles are normal. How much, and how often do you add?

You can have someone raise the RPM's a tad when the thermostat opens, (Coolant moving) then add coolant. This will help bleed out air. Without a recovery tank though, it probably will push the added fluid out onto the ground.

There are other tricks like filling up radiator with your car on a hill, drilling small holes in thermostat. Make sure the car is hot when you add to it, the heater needs to be flowing also.

twilightcall · 06-09-2003, 05:02 PM

Sorry about that. It is an 83' and I put coolant in at the radiator. It hasn't needed it. I just put some in. I let it idle with the A/C on high and after about 10 minutes the highest it got was almost to 3/4s. As soon as I gave it a little throttle it went down to almost halfway. Is the normal way to bleed the system to leave the cap off and run it until the thermostat opens? Thanks. It is a 5.0.

mustangII460 · 06-09-2003, 07:28 PM

Cap off, wait till the stat opens. Gently raise up the RPM's and watch the level sink/add fluid now. Cap radiator while RPM's are still up. If you let down the RPM's with the cap off at this point , the fluid added will push out.

06-09-2003, 04:08 PM	#1
twilightcall Registered Member Join Date: May 2003 Posts: 86	Airbubbles in radiator, normal or should I worry? I checked the coolant level in my car today. It was a little low so I topped it off. I started the car and left the cap off. Once it was start I saw a bunch of small air bubbles come up through the coolant and the level went down a little. After about 10-20 secs. the air bubbles stopped and the coolant gradually rose back up. After that I saw no more air bubbles. I checked my oil and there was no coolant in the oil. Is this normal or is this a sign of a headgasket issue? How do you bleed air out of this system? I didn't see a bleed screw on the rad. or on top of the therm. housing. Thanks for the help.

06-09-2003, 04:24 PM	#2
mustangII460 Factoy Five Roadster Join Date: May 2000 Location: Sevier Co,Tennessee Posts: 1,681	You didn't post what year car or motor etc. Low in the recovery tank? Or just in the Radiator? Some coolant will get pushed out/burned off. A few bubbles are normal. How much, and how often do you add? You can have someone raise the RPM's a tad when the thermostat opens, (Coolant moving) then add coolant. This will help bleed out air. Without a recovery tank though, it probably will push the added fluid out onto the ground. There are other tricks like filling up radiator with your car on a hill, drilling small holes in thermostat. Make sure the car is hot when you add to it, the heater needs to be flowing also. __________________ Frank Last edited by mustangII460; 06-09-2003 at 04:30 PM..

06-09-2003, 07:28 PM	#4
mustangII460 Factoy Five Roadster Join Date: May 2000 Location: Sevier Co,Tennessee Posts: 1,681	Cap off, wait till the stat opens. Gently raise up the RPM's and watch the level sink/add fluid now. Cap radiator while RPM's are still up. If you let down the RPM's with the cap off at this point , the fluid added will push out. __________________ Frank

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06-09-2003, 05:02 PM	#3
twilightcall Registered Member Join Date: May 2003 Posts: 86	Sorry about that. It is an 83' and I put coolant in at the radiator. It hasn't needed it. I just put some in. I let it idle with the A/C on high and after about 10 minutes the highest it got was almost to 3/4s. As soon as I gave it a little throttle it went down to almost halfway. Is the normal way to bleed the system to leave the cap off and run it until the thermostat opens? Thanks. It is a 5.0.