11 31 051 Replacing timing chain (N55) from March 2012

Special tools required:

Necessary preliminary tasks:

Remove CYLINDER HEAD COVER .
Remove all SPARK PLUGS .
Remove CRANKSHAFT SEAL at front
Remove TENSIONING DEVICE for drive belt.
Remove VIBRATION DAMPER .
Check TIMING .
Remove SEALING COVER for vacuum pump.
Remove SEALING CAP of chain tensioner for oil pump.

Engine removed:

Block crankshaft with special tool 11 9 260 .

IMPORTANT: To release central bolt (1), remove special tool 11 0 300 .

Fig 1: Blocking Crankshaft With Special Tool (11 9 260)

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IMPORTANT: When central bolt of crankshaft is released, there is no longer a secure connection to timing drive.

Mark position of crankshaft using a colored mark (1).

This will make future insertion of special tool 11 0 300 easier.

Fig 2: Colored Mark On Crankshaft

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Block crankshaft with special tool 11 8 660 .

Fig 3: Blocking Crankshaft Using Special Tool (11 8 660)

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IMPORTANT: Before releasing the central bolt, the hydraulic chain tensioner must be drained.

Carefully press tensioning rail (1) with a suitable screwdriver (2) in direction of arrow.

Fig 4: Pressing Tensioning Rail Using Screwdriver

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As the oil pressure in the chain tensioner can only be drained pulsating, the tensioning rail (1) must be pressed several times.

Press the tensioning rail (1) and hold down.

Fix chain tensioner piston in position with a suitable lock pin (2).

Fig 5: Identifying Tensioning Rail And Lock Pin

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IMPORTANT: Breakaway torque of the central bolt > 600 Newton meters
A 3/4-inch tool (large powered square) is required to release central bolt.

Release central bolt (1) with 3/4-inch tool (2).

Tightening torque 11 21 1AZ .

Fig 6: Releasing Central Bolt With 3/4-Inch Tool

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Remove CHAIN TENSIONER .

Screw in vibration absorber screws (1).

Move hub (2) on crankshaft forward in direction of arrow to remove.

Fig 7: Pulling Crankshaft Hub

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Open screw plug (1).

Tightening torque 11 31 8AZ .

Fig 8: Identifying Screw Plug

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Open screw plug (1).

Tightening torque 11 11 7AZ .

Installation note:

Replace aluminum screws.

Fig 9: Identifying Screw Plug

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Release bearing journal (1) from timing chain module on cylinder head.

Tightening torque 11 31 6AZ .

Fig 10: Identifying Bearing Journal

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IMPORTANT: Install special tool 11 4 280 to release the central bolts on the intake and exhaust camshaft adjusters.

Remove INTAKING AND EXHAUST CAMSHAFT ADJUSTERS .

Fig 11: Identifying Special Tools

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Release bearing journal (1) from timing chain module on crankcase.

Tightening torque 11 31 5AZ .

Fig 12: Identifying Timing Chain Module Bearing Journal

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Release bolts (1) from timing chain module on cylinder head.

Tightening torque 11 31 4AZ .

Remove chain module with timing chain and camshaft sprocket upwards in direction of arrow.

NOTE: Illustration shows N52.

Fig 13: Removing Timing Chain And Sprocket

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IMPORTANT: Note direction of installation of camshaft sprocket (2).
Collar (see arrow) on camshaft sprocket (2) points to engine .
Incorrect assembly will result in engine damage .

Fig 14: Locating Collar On Camshaft Sprocket

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Pull timing chain (1) upwards until camshaft sprocket (2) engages chain guide (3).

Install timing chain (1) and camshaft sprocket (2) in this position.

Installation note:

Always hold timing chain (1) under tension. Timing chain (1) may jam on chain guide (3).

Fig 15: Identifying Timing Chain, Camshaft Sprocket And Chain Guide

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Insert central bolt (1) with hub for crankshaft.

Tighten down central bolt (1).

Tightening torque 11 21 1AZ .

Install INTAKING AND EXHAUST CAMSHAFT ADJUSTERS .

Install CHAIN TENSIONER .

Fig 16: Tightening Central Bolt With Special Tool (00 9 140)

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Crank engine twice.

Check TIMING .

If necessary, adjust VALVE TIMING .

Replace front CRANKSHAFT SEAL .

Assemble engine.