Hi, I have read the many coolant bleeding ways on the forum, but I am having no luck. Firstly the car would not get up to temperature, so I have changed the thermostat. Now the car gets up to temperature, gets the 90 degrees and then drops all the way back down and the temperature gauge wont move. My thinking is an air lock, so I started the car up, heater on full hot and full speed and left it running with the cap off and the heater matrix pipe slightly off. After doing this for 40minutes and air bubbles coming out the of the expansion but still no coolant coming out of the bleed hole. I reverted to blowing down the expansion main opening and forcing coolant out of the bleed hole which worked, it also worked when i revved the engine, but on idle nothing would exit the bleed hole. Any ideas?