I think I have an air pocket in my cooling system and the WSM I just bought is less than clear on removing the trapped air via the bleeder screw? Do I open the bleeder valve when engine is cold to release any air trapped and then, start the car and keep open until the car is up to temp or do I close it and then reopen when the car is at temperature (which seems dangerous) ? It states to have the heater dial turned all the way up but does not say to start the engine (?) Thanks for any help guys, I know this must be a simple task but I just do not know. Will I hear the air escape ?