I changed the radiator on my 89SC, do I have to open the bleeder screw on top of the intake? I did not do it, filled the radiator and the overflow bottle,let it run 5 minutes,shut it off,checked the fluid level,was little low,topped it off again. Checked it again next day,radiator is full. LOW radiator light is on,where is the censor, is it in the overflow bottle? Is it supposed to have coolant there at all times? Thanks.....!