Spot on Bezerkr32,
It is the Viscus fan cupling/clutch, as you said when the viscus oil heats up it releases the clutch and allows the fan to spin freely, and that is stuffed just from age so it is not releasing and spining with the engine revs hense the car sounding like a bus!!!. Have purchased a second hand fan and cupling for $100 and fitting it this weekend.
Thanks for all your suggestions those who posted.
Cheers
Jamie