An airpocket will not cause leaks. It will cause the car to possibly overheat but it will not cause leaks. If there is no external leaking then the only other place it can go is into the cylinder bore,
. Pressure check it and find out if it holds pressure. If the raidator is full it will not suck in air if you have the cap off. If you have an airpocket it will work it's way ouyt but it won't make the system leak. Maybe your radiator cap is shot and not allowing the pressure to escape. When you pressure check the system, check the cap also and see if it let's go where it should. I think the Mustang cap is 15-17lbs, I'm not sure. It says on the cap itself. Let us know brother!
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87 GT
Full exhaust, K&N, KB Subs, BBK STB, homeade dumps...
87 Taurus
New York
Winters Bite!