Remove/install chain tensioner - AR05.10-P-7800SX

ENGINES 273 in MODEL 216 

ENGINES 272, 273 in MODEL 221 

Fig 1: Identifying Chain Tensioner Remove/Install Components (1 Of 2)

Courtesy of MERCEDES-BENZ USA

Fig 2: Identifying Chain Tensioner Remove/Install Components (2 Of 2)

Courtesy of MERCEDES-BENZ USA

	Removing
1	Detach ground line(s) from battery/batteries		AR54.10-P-0003SX
	Notes on battery		AH54.10-P-0001-01A
2	Rotate engine at crankshaft center bolt in direction of engine rotation to a 40° crankshaft angle after ignition TDC		Figure
3.1	Detach connector for circuit 61 (D+) from alternator and remove alternator from timing case cover (2)	Except model 221.095/195 The alternator remains with its attached line for circuit 30 (B+) in the engine compartment.	AR15.40-P-5032SX
3.2	Remove alternator	Model 221.095/195	AR15.40-P-5032SXH
4	Remove chain tensioner (1) from timing case cover (2)
	Install
5	Screw new chain tensioner (1) into timing case cover (2) and tightened to prescribed torque	Replace chain tensioner (1)  . The previously installed chain tensioner must not be reinstalled since, on removal of pressure bolt (1a), it is pressed into the end position and the locking device of the pressure bolt prevents its return stroke. This would overstretch the timing chain on reinstalling.
			*BA05.10-P-1008-01B
6	Remove cap (3)
7	Turn engine at center bolt on the crankshaft with prescribed torque against direction of engine rotation  (arrow), while counterholding left exhaust camshaft (4) at rear with a suitable tool	This unlocks the chain tensioner (1).
			*BA05.10-P-1009-01B
8	Rotate engine at center bolt for crankshaft in direction of engine rotation  by a 90° crank angle	The thrust pin (1a) for chain tensioner (1) will be pushed out and tensions the timing chain.
9	Install end cover (3)
10.1	Attach connector for circuit 61 (D+) and mount alternator on timing case cover (2)	Except model 221.095/195	AR15.40-P-5032SX
10.2	Install alternator	Model 221.095/195	AR15.40-P-5032SXH
11	Mount ground line(s) from battery/batteries		AR54.10-P-0003SX
	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
12	Carry out an engine test run and check engine for leaks

Fig 3: Identifying Wrench Socket (001 589 65 09 00)

Courtesy of MERCEDES-BENZ USA