91 Mercury Topaz thermostat where is it?

The thermostat on a 1991 Mercury Topaz is typically located on the engine block, near the intake manifold. To access it, you'll generally need to remove the upper radiator hose and the thermostat housing, which is usually secured by bolts. Once you remove the housing, you should see the thermostat seated in a recess in the engine. Always consult a repair manual for specific instructions related to your vehicle model.