Remove/install coolant thermostat - AR20.10-P-2460SX

ENGINES 272, 273 in MODEL 221 

ENGINES 273 in MODEL 216 

Fig 1: Identifying Coolant Thermostat Remove/Install Components - Shown On Engine 273

Courtesy of MERCEDES-BENZ USA

Shown on engine 273 

	Remove/install
1	Switch off ignition
2	Drain coolant at radiator		AR20.00-P-1142SX
	Notes on coolant		AH20.00-N-2080-01A
3	Remove left engine intake air duct and front engine cover	See Remove air filter housing.	AR09.10-P-1150SX
4.1	Detach top coolant hose (1) from coolant thermostat housing (2) and place it on the side	Vehicles without 4MATIC Replace O-ring (1a).
4.2	Remove coolant pipe	Vehicles with 4MATIC
		See "Removing power steering expansion reservoir".	AR46.25-P-1000SX
5	Remove poly-V belt and guide pulley (3)	Except model 221.095/195 with a twin belt drive	AR13.20-P-0001SX
	Version of the poly-V belt altered	Model 221.095/195	BT13.20-P-1000-01SXH
6	Unlatch electrical connector at three-disk thermostat valve (Y110) and disconnect
7	Remove screw/bolts (2a, 2 pieces)		*BA20.10-P-1003-01U
8	Pull out coolant thermostat housing (2) with coolant thermostat from timing case cover	The coolant thermostat must not be taken out of the coolant thermostat housing (2) as it can get damaged in the process. Replace gasket (2b) and O-ring (2c).
9	Install in the reverse order
	Checking
	Risk of accident  caused by vehicle starting off by itself when engine is running. Risk of injury  caused by contusions and burns during starting procedure or when working near the engine as it is running	Secure vehicle to prevent it from moving by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.	AS00.00-Z-0005-01A
10	Conduct engine test run and check engine for leaks