Where is the thermostat located on a 1998 Buick Century?

The thermostat on your 1998 Buick Century is located on the engine block, to the right of the cylinder head, near the water outlet neck for the radiator hose. It is cylindrical, with a single electrical connector coming out of the top. To replace it, remove the two bolts holding it in place and disconnect the electrical connector. Be sure to install the new thermostat in the same orientation as the old one, with the jiggle valve pointing up.