Hi people, having read numerous threads on here about this I've tried to do most of what's been suggested, things I've done so far are; compression test, all good / checked thermostat with snap-on diagnostic, full flow at 98 degrees / replaced viscous fan / replaced water pump (old one seemed ok but .....) / tried to do a sniff test but as there are no signs of bubbles, nothing happened / replaced expansion tank cap. But, it will only run for about 6 miles before temp starts to rise, the air con fans kick in but make little difference, it's only when I put heater on full I can drive it but it's bloody hot. Lifting the bonnet after a short run I can hear water either bubbling in the system or flowing around it, wearing hearing aids means I can't pin point where the noise is coming from, it seems to be the mass of pipes to the left of the plenum chamber. I haven't got much hair left so any help would be very much appreciated