How can air get into the cooling system?

[JShakey]

I have had this issue off and on for several years now. I have done all the tests head gasket / intake gasket . Did have to put head gasket repair in it. Today i was driving and lost all power. Looked at the gauges and the temperature was buried on high. I quickly pulled over and raised the hood expecting to see antifreeze everywhere. The overflow bottle was completely full and bubbling so i figured it had air in the system . I let it set for 45 minutes on the side of the road. The level in the overflow did not go down any. I know that opening the bleeder valves with the temperature so high can just cause the coolant to boil , but i did open it a little and a ton of air came out . It did start blowing steam after several minutes which is when i closed it off, and just sat there another 15 minutes. I looked at the level again and it had completely dropped to normal. I was able to go ahead and drive it home and the temperature never went over the mark below halfway. I have been researching this since getting home, can there be a leak on one of my quick connects for my heater core causing this or am i going to have to try and do the head gasket? It has gotten very frustrating.

 

[melsg5]

have you pressure tested the cooling system including the radiator or expansion tank cap?
have you done a hydrocarbon test of the the cooling system fluid to test for another blown head gasket?
with the AC on does the electric radiator fan turn on?
when the car overheated was the electric radiator fan running?
sounds to me changing the thermostat might be a good idea.
the over flow bottle was was perhaps bubbling because you exceed the boiling point of the coolant

 

[JShakey]

Have not done a pressure test since the last issue with the head gasket. The expansion tank just has the plunger type lid that you push down into the bottle. I will also be doing the carbon test as well. Yes the fans were running when it overheated and they ran with the AC on. It is a brand new thermostat , changed with the water pump 2 years ago. Also i was running the heater when i was driving it home yesterday and it would blow hot air when I was going straight but when i made a right turn the air went cold. Isn't that a sign of air pockets?

 

[davidawg]

Heater core may be plugging up try flushing it out

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[melsg5]

the air pockets have to be accompanied by a loss of coolant caused by a leak, thus the pressure test including any pressure cap in the system.

 

[JShakey]

Ok sorry for the late response. It was the head gasket again. Drained the entire cooling system and bought the most expensive over the counter head gasket repair I could get . It was Blue Devil but this time it wasn't the pour and go . I let it sit for several days to set and it seems to be working good now.