over heating?

My movano van is 03 with a 2.5 reault diesel. It drives perfect, pulls like a train, but after 3 miles or so of normal driving, the tempreture gauge will move in seconds from normal to red hot. There is no smoke from exaust, the water in the header tank bubbles hot, but the fan is not going and the bottom hose is cold. I suspect the head gasget, but my mate has just had an overheating problem on his Isusu pick up. The head gasget was changed, but it still over heared. It turned out all the veins had broken off the impeller on the water pump. As this a possibility on my van.