The heater never really got red hot while iv had the car i put that down to losing water. the heater is better now when the car is stood just when driving it goes really cold and the temp drops to nearly the last line with the C on it is acting like the stat is gone but thats new and there was nothing wrong with the old one either.
Im hoping it is a air lock i used to be a mechanic for 10 years just never worked on a lexus and one of my mates said he did a water pump on a audi doing the same thing and the propeller had feel off the back of it so i will have to see how it acts going to work today thanks for the reply