No, you do not necessarily have to but it is a good idea. Have the entire system flushed. Replace the thermostat, bleed the system. I would also replace all coolant hoses at this time unless you have done so before. Your car is 14 years old and although they may look OK, it is just smart to replace now before you are stranded by a hose bursting. Be sure and replace the heater hoses also. Refill the system with a 50/50 mixture of anti-freeze and distilled water.
mercury sable
To change the thermostat on a 2002 Mercury Sable, first ensure the engine is cool, then disconnect the negative battery cable. Drain the coolant from the radiator, remove the upper radiator hose from the thermostat housing, and unbolt the thermostat housing. Replace the old thermostat with a new one, ensuring it's oriented correctly, reassemble the housing, reconnect the hose, refill the coolant, and finally reconnect the battery.
On a 2002 Mercury Sable the radiator is at the front of the engine compartment
It is located where the upper radiator hose connects to the engine.
On a 2000 Mercury Sable, the thermostat is typically located at the engine end of the upper radiator hose, where it connects to the engine. To access it, you may need to remove the upper radiator hose and the thermostat housing. Ensure the engine is cool before attempting to locate or replace the thermostat to avoid burns or injury.
There is a thermostat on all cars.
front of the motor
On a 2003 Mercury Sable : The thread on cap on the engine coolant reservoir is the 16 PSI pressure cap / radiator cap
On a 2002 Mercury Sable : The thread on cap on your engine coolant reservoir is the 16 PSI pressure cap / radiator cap
99% sure the Taurus radiator will be a perfect match to the Sable's.
In a 2000 Mercury Sable : The thread on cap on the engine coolant reservoir is the pressure cap / radiator cap
The thread on cap on the engine coolant reservoir of a 2002 Mercury Sable is the pressure cap / radiator cap