[EMBPilot]

i would disconnect your battery, disconnect the fans, then remove the fan housing from the radiator. using the drain plug, you may only need to drain about two liters out of the system to get the coolant level below the thermo switch.

the wire clip should come off the back of the thermo switch with a gentle tug. you'll need a deep 30MM socket for the thermo switch and a new crush washer, i think it happens to the be same washer as the oil pan plug crush seal. i think the torque on the thermo switch is 28NM ?.
i just did this when i replaced my rad.