[veedubmechanic]

either the coolant resivour is faulty (for some reason 02 1.8t is a bad jeat for manufacturing the coolant resivour)

or the water pump is faulty ( rev it in nutral when warmed up to 5-6k fast and if there is a metal clink sound when you let off the gas the w-pump is bad) sometimes the impellar is not broke but when its gets really hot from highway driving or stop/go the impellar actually loosens itsself from the shaft and then cools down and re-attaches isself (its actually how they assemble them at the factory... pretty cheap)