1991 BMW 850I Engine And Engine Coolingengine Problems

THIS CAR LOSES COOLANT, OVERHEATS, AND BLOWS A HEAD GASKET, AND NOW POSSIBLY NEEDS NEW CYLINDER HEADS. BMW MECHANIC STATES THAT THE TEMPERATUTE GAUGE IS NOT SUPPOSED TO TELL YOU THE ENGINE IS OVERHEATING IF THE COOLANT HAS ALREADY COMPLETELY LEAKED OUT OF THE SYSTEM. THAT THE GAUGE DOES NOT REGISTER THE EMPTY AIR IN A NOW EMPTY COOLANT SYSTEM. IN MY OPINION THE TEMP GUAGE SHOULD TELL ME THE POSSIBILITY OF MY CAR OVERHEATING SO THAT I CAN SHUT DOWN THE ENGINE AND HAVE IT REPAIRED. THIS HAS OCCURRED TWICE($5,000 FIRST TIME) AND NOW AN ESTIMATED $9,000-15,000 DEPENDING ON EXTENT OF DAMAGE. PLEASE SEND ANY INFORMATION YOU MAY HAVE ON THIS PROBLEM WITH THIS VEHICLE. A LOCAL REPUTABLE IMPORT REPAIR SHOP INFORMED ME THAT THIS HAPPENS WITH THIS CAR AND THAT THEY CONSIDER IT A COMMON DEFECT/OCCURRENCE. TO COMBAT THIS THEY EVEN HAVE THEIR OWN SOLUTION MY DRILLING EXTRA...