The thermostat on the 1999 Ford Taurus 3.0L DOHC 24-valve engine is located on the passenger side of the engine block, just below the upper radiator hose connection.
Procedure to Replace the Thermostat:
1. Allow the engine to cool down completely to avoid any risk of burns.
2. _Locate the thermostat housing_ at the bottom of the upper radiator hose connection on the passenger side of the engine block.
3. _Use a 10mm socket or wrench_ to loosen and remove the two bolts that secure the thermostat housing to the engine block.
4. Carefully remove the thermostat housing along with the old thermostat from the engine.
5. _Inspect the old thermostat_ and compare it with the new one to ensure they are the same size and type.
6. _Place the new thermostat into the housing_ with the jiggle valve positioned upwards and the gasket facing the engine.
7. Reinstall the thermostat housing and secure it using the two bolts you removed earlier.
8. _Reconnect the upper radiator hose_ to the thermostat housing and tighten the hose clamp securely.
9. _Refill the coolant reservoir_ with a mixture of 50% coolant and 50% distilled water.
10. Start the engine and let it run for a few minutes to ensure the thermostat is working properly.
Note: It's recommended to replace the thermostat along with the thermostat gasket during the replacement process to ensure a proper seal and prevent any potential leaks.
