1. Disconnect the battery.
Locate the battery in the trunk of your Mercedes. Remove the negative (black) cable from the battery using a wrench.
2. Drain the coolant.
Place a large drain pan under the car to catch the coolant. Open the drain plug on the bottom of the radiator. Allow all of the coolant to drain out.
3. Remove the fan shroud.
Remove the bolts holding the fan shroud in place, and then remove the fan shroud.
4. Remove the old thermostat
Locate the thermostat housing on the front of the engine. Remove the bolts that hold the thermostat housing in place. Remove the old thermostat from the housing.
5. Install the new thermostat
Insert the new thermostat into the housing. Make sure the thermostat is seated correctly. Replace the bolts that hold the thermostat housing in place.
6. Refill the coolant
Add the coolant to a 50/50 mix with distilled water until it reaches the "FULL" mark on the coolant reservoir. Make sure all the air is out of the cooling system.
7. Reconnect the battery.
Reconnect the negative cable to the battery.
8. Start the engine and run it for 15 minutes.
Check for any leaks from the cooling system.
