to much pressure

hi all. i have a 95 300tdi. as soon as i start the engine water starts spraying out from the thermotsat houseing and the header tank. the temp guage is sitting where is should at the half way mark but its overheating.the heater dont blow hot air. i have been told that it could be head gasket. is there anything else it can be?

thanks craig

OH YES, Mine did the same, the pressure built up so much that it split the header tank and water sprayed out of there like a fountain.
Defo the head gasket, filled mine up with water, took the cap off the header tank and was able to drive it with the temp gague on the half way mark for 10 miles to my local garage, dont keep running it like it is! Get it sorted now before it frys more than it should