I think that is due to cooling issues, from the Stag version of Aulro and by a L-R/British car expert Greg Tunstall here in Brisbane TSOAQ - Maintaining Your Stag's Cooling SystemQuote:
Originally Posted by Old Farang
"All the original complaints about STAG Cooling system were probably justified and usually related to the fact that the sand cores was not always fully removed from the engine block after casting, and in use, ended up in the radiator. The other real problem was/is that the internal water pump is high in the block and if the engine has slight water loss, then the pump is left high and dry, the water starts to boil around the heads.These problems are not aided by the inaccurate sensor/gauge and/or the high mounted temp sensor that ceases to read when the water level drops below the sensor level, or the nature of the aluminium heads themselves, which expand greatly when overheated. This expansion usually results in loss of head bolt tension and subsequent blown head gasket when refilling and re-starting. The must-do here, is to re-torque the heads if you ever boil a STAG, this needs to be done before refilling with coolant or restarting,........"
