Thermostat (Thermostat Housing), Remove and Install (C 18 XE, C 18 XEL, C 18 SEL, X 18 XE, X 20 XEV)
Notice:
The thermostat is only supplied in assembly with the thermostat housing for warranty reasons.
Remove, Disconnect
Remove lower radiator hose from radiator - collect coolant.
Detach upper radiator hose (1) from thermostat housing and remove thermostat housing (2) from cylinder head.
Clean
Clean sealing surfaces and remove sealant remnants.
Install, Connect
Attach thermostat housing to cylinder head with new seal ring - 15 Nm/ 11 lbf. ft.
Attach radiator hose to thermostat housing and lower radiator hose to radiator.
Inspect
Cooling system - see operations "Cooling System, Top Up and Bleed" and "Cooling System, Check for Leaks".
Remove, Disconnect 
Clean 
Install, Connect 
Inspect