The water pump and/or the plastic side tanks on the radiator may leak causing a loss of coolant. The engine may overheat due to coolant loss. Continued coolant loss after external leaks have been repaired could indicate a blown head gasket.Google+
Car Problem Reports
Cadillac Seville Coolant Leaks From Water Pump and Radiator
Cadillac Seville Problem
Visitor, 2002 Cadillac Seville, 63,000 mi
Happened again at 110,000 miles. Replaces thermostat housing and water pump both times.