Remove/install primary drive timing chain - AR05.10-P-7612MMB

ENGINE 157, 278 in MODEL 216, 221 

Fig 1: Identifying Primary Drive Timing Chain Remove/Install Components (1 Of 3)

Courtesy of MERCEDES-BENZ USA

Fig 2: Identifying Primary Drive Timing Chain Remove/Install Components (2 Of 3)

Courtesy of MERCEDES-BENZ USA

Fig 3: Identifying Primary Drive Timing Chain Remove/Install Components (3 Of 3)

Courtesy of MERCEDES-BENZ USA

	Remove/Install
1	Remove cylinder head covers	Left cylinder head cover	AR01.20-P-5013MMB
		Right cylinder head cover Before assembly of the cylinder head covers the timing of the engine must be checked and corrected if necessary.	AR01.20-P-5012MMB
2	Remove timing case cover		AR01.40-P-8000MMB
		The timing of the engine must be checked and corrected if necessary before assembly of the timing case cover.
3.1	Remove camshafts	For missing color codings on the segmented discs (1AL, 1AR, 1EL, 1ER).
			AR05.20-P-6992MM
3.2	Remove the right exhaust camshafts adjuster (8AR) and left intake camshafts adjuster (8EL)	For color codings present on the segmented discs (1AL, 1AR, 1EL, 1ER).
			AR05.20-P-7201MMB
4	Mark segmented discs (1AL, 1AR, 1EL, 1ER) for camshafts relative to the cylinder head contact surface (01) in color (see arrows in picture)	For missing color codings on the segmented discs (1AL, 1AR, 1EL, 1ER).
			AR05.20-P-6292-04MM
		Template	Fig 4
5	Remove oil pump		AR18.10-P-6020MM
6	Remove chain tensioner for primary chain drive timing chain (6)	Replace chain tensioner for primary chain drive timing chain (6).
		Screw/bolt, chain tensioner to cylinder crankcase/cylinder head	*BA05.10-P-1001-01R
7.1	Remove both cylinder heads	For replacing the primary chain drive timing chain (6) and secondary chains (05L, 05R) with slide and tensioning rails.
		Left cylinder head	AR01.30-P-5770MMB
		Right cylinder head	AR01.30-P-5780MMB
7.2	Disconnect left secondary chain (05L) and right secondary chain (05R)	For replacing the left and right secondary chain (05L, 05R) without slide and tensioning rails.
			AR05.10-P-7601MM
		For a timing chain stretch the left and right secondary chain (05L, 05R) and the primary chain drive timing chain (6) should be replaced.
8	Remove right secondary chain (05R) from intermediate gear (7)
9	Remove screw/bolt for intermediate gear (7) on cylinder crankcase	The screw/bolt must be replaced after every disassembly.
		Screw/bolt, journal for intermediate gear to cylinder crankcase	*BA05.10-P-1004-01R
10	Remove the intermediate gear (7) together with the crankshaft gear, primary chain drive timing chain (6) and left secondary chain (05L)	The primary chain drive timing chain (6) must be mounted in such a way that the primary chain marking (3) and the punch mark (4M) on the intermediate gear (7) and crankshaft gear match. Engine damage will occur otherwise. The intermediate gear must be mounted together with the primary chain drive timing chain (6) and the left secondary chain (05L). A new primary chain drive timing chain (6) and secondary chain (05L, 05R) are delivered optionally with color codings or copper links. Replace intermediate gear (7) with journal.
11	Install in the reverse order
	Check
12	Check basic position of camshafts		AR05.20-P-6010MM
		The timings of the engine must be checked and corrected if necessary before assembly of the cylinder head covers and the timing case cover.
	Risk of accident  from vehicle starting off by itself when engine running. Risk of injury  (bruises and burns) resulting from working on the engine while it is being started or when it is running.	Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.	AS00.00-Z-0005-01A
13	Perform an engine test run; in doing so check engine for proper operation and leaktightness

TIMING CHAIN, CHAIN TENSIONER

Number	Designation		ENGINE 157	ENGINE 278
BA05.10-P-1001-01R	Screw/bolt, chain tensioner to cylinder crankcase/cylinder head	Nm	9	9

TIMING CHAIN, CHAIN TENSIONER

Number	Designation			ENGINE 157	ENGINE 278
BA05.10-P-1004-01R	Screw/bolt, journal for intermediate gear to cylinder crankcase	M10	Nm	55	55

Fig 4: Identifying Template (278 589 00 23 00)

Courtesy of MERCEDES-BENZ USA