Hi i have changed radiator, thermostat switch, external water tank but still my car is overheating after a long drive around 150 kms. when overheats water coming out (bubbling) from external tank & some times fans working & some times not working. recently 3 months back i found water leak from near brake pedal when i used the Heater. then i closed water connection completely to heater & i am not using heater. since then there is no problem for 3 months. but again same problem started & no water leaking. kindly help me to fix this please.