1985 MITSUBISHI MIGHTY MAX Engine And Engine Cooling Problems

THIS VEHICLE IS A 1985 MITSIBISHI D-50 DIESEL PICKUP.EVERY THING HAS WORKED FINE UNTIL OCTOBER WHEN THE ENGINE TEMP OVERHEATED AND I BEGAN TO LOSE COOLANT OUT OF THE EXPANSION TANK. NOTED ALSO THAT THE TEMPRATURE GUAGE DID NOT READ HIGH . THE VEHICLE WAS TAKEN TO MITSIBISHI OF SAN DIEGO FOR EVALUATION OF OTHER PROBLEMS AS WELL AS THIS,AND WAS TOLD NOT TO WASTE ANY MONEY ON IT BECAUSE THE HEAD WOULD CRACK GUARANTEED AT 50,000 MILES .