I had this problem. What I noticed is that (well for me) it had a pattern. What mean is it would pulse/flash when it was warm so that made me know were the air was coming in at. Then I just kept bleeding for 4 hours then it stop. Stupid smog guy opened it back up and let air in now I have to do it all over again. If you think there is air keep bleading it. The main point of air that could be entering is through the recovery tank check it to make sure you have fluid in there.