> Have you checked the drive belt (fan and AC) idler pulleys?
> >
> The belts where changed a little while ago, but I would be surprised if
> they could make that sort of noise with a rubber belt, unless there is
> actually stuff floating around inside them, but then it would happen at
> all temperatures.
It's not the belt that makes the noise but the idler pulley bearings. Does sound rather like timing chain problems - and is a very common failing on this engine.
My feeling was that because its temp related it likley to be something
> to do with oil and component wear. Anythings possible I suppose.