hi my radiator keeps over flowing all the time and the colant kept filling up the expansion bottle next to the radiator. so i changed the cap, flushed it out and had same problem. now ive left it alone for a few days and havent topped the radator up to the top and it doesnt overflow. so my qustion is when filling the radator with coolant should u fill it right to the top just before the coolant comes out or leave enough space for cap to go on?

thanks

 

Its just more than it needs. I would fill it full start the motor, let it cycle the coolant. then check it. Top it off through the overflow tank.