The lower intake gaskets have most likely failed, and you are very low on coolant or there is air in the cooling system.
drain coolant then remove thermostat housing remove thermostat replace with new one spring to block
Drain the radiator. Remove the top radiator hose on the 2003 Buick Century. Unbolt the hose inlet. Remove the inlet housing and take out the thermostat. Replace the thermostat, install the housing and top hose, and refill with antifreeze.
The thermostat is located in the top radiator hose connector. The top hose and the housing need to be removed for access.
Its the bleeder screw, its used to let air pockets out the coolant system.
Look in the removable housing at the engine end of the upper radiator hose
Look in the housing located at the engine end of the upper radiator hose
The thermostat is located in the top radiator hose connector. The top hose and the housing need to be removed for access.
Should be in a removable housing at the engine end of the upper radiator hose
It is in the block just below the thermostat housing on the driver's side of the engine. If you follow the radiator hose from the radiator to the thermostat housing, just below and to the left of the hiusing you will see the wires to the thermostat. Pull back the clip and remove the wires to gain access. Takes a 3/4 wrench to remove the sensor.
Drain the radiator. Remove the 91 Centurys top radiator hose. Unbolt and remove the top water inlet on the engine. Pull the thermostat from under the housing. Install the thermostat, a new gasket, and reinstall the inlet and top hose before filling the system with new coolant.
remove the thermostat housing
Follow the top radiator hose back to the engine. The thermostat is behind the housing that connects the top hose to the engine block.