my coolant is full. the resevoir is full. the bleeder cap on my car is busted and wont open. i plump the lines to get rid of the air, except the buzzer will not stop. it typically buzzes only when in gear, if i take her out of gear the buzzing stops temporarily. is it a leak? i have placed cardboard under the car and left it overnight, no spots at all, and there is no visible leak anywhere under the hood. could the lines be plugged? i dont get it, except i know i am getting a migrane from the buzzing.