Thermostat, Remove and Install (C 20 XE)
Remove, Disconnect
Remove lower radiator hose from radiator - collect coolant.
Detach coolant hose (1) from thermostat housing.
Remove fastening bolts (2) and remove thermostat.
Clean
Clean sealing surfaces and remove sealant remnants.
Install, Connect
Install thermostat on thermostat housing with new seal ring - 15 Nm/11 lbf. ft.
Install/attach radiator hoses.
Inspect
Cooling system - see operations "Cooling System, Top Up and Bleed" and "Cooling System, Check for Leaks".
Remove, Disconnect 
Clean 
Install, Connect 
Inspect 