first you will have to drain the fluid out of the radiator. Make sure you check the pressure of the large hose going to the radiator. It it is hot and hard, don't remove the radiator cap. wait until the engine is cool. After draining the fluid, disconnect the hoses running to the radiator one by one. mark each one so that you place them back in the correct place. Remove the bolts or srews on both sides of the radiator top and bottom. it should lift right out. OH yeah you will make a big mess but that's ok.
On a 2002 Mercury Cougar : No , the thread on cap on your engine coolant reservoir is the pressure cap / radiator cap
Remove both upper and lower radiator hoses and run your garden hose water through from the top opening.
Should be in a removable housing at the engine end of the upper radiator hose
In North America the last model year for the Mercury Cougar was 2002
On a 2002 Mercury Sable the radiator is at the front of the engine compartment
A 2002 Mercury Cougar 2.5 liter plug wire diagram can be purchased from your local Mercury Cougar. It can also be found at most auto parts stores.
ECM reset for 2002 merc couger