The coolent bottle could be filled up and would alway drop to minimum noo lower. He overtaken at car and then realised 2minz after his temperature was at 110 so switched it of and checked coolent. There was none in the bottle until the pressure was released then if filled back up then the car had cooled down. its been topped up and is in use covered around 15miles and still ok not reaching above 90. the coolent in the bottle isn't getting hot but the pipe into tope of radiator is! Any ideas or what it may be would be much appreciated thank!!!!