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: Releasing Central Bolt

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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: Identifying Crankshaft Mark

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Vehicles with automatic transmission:

Block crankshaft with special tool 11 8 660 .

Fig 3: Identifying Special Tool (11 8 660)

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Vehicles with manual gearbox:

Attach special tool 11 8 180 to manual transmission with existing transmission bolts (1).

Block crankshaft in direction of arrow with special tool.

Fig 4: Attaching Special Tool (11 8 180) To Manual Transmission

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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.

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

Fig 5: Pressing Tensioning Rail

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Press the tensioning rail (1) and hold down.

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

Fig 6: Adjusting Chain Tensioner Piston Position

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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 7: Removing Central Bolt

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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 8: Moving Hub On Crankshaft

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Open screw plug (1).

Tightening torque: 11 31 8AZ .

Fig 9: Identifying Screw Plug

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Open screw plug (1).

Tightening torque: 11 11 7AZ .

Installation note:

Replace aluminum screws.

Fig 10: Identifying Screw Plug

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

Tightening torque: 11 31 6AZ .

Fig 11: Releasing Bearing Journal From Timing Chain Module On Cylinder Head

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

Remove INTAKE AND EXHAUST CAMSHAFT ADJUSTERS .

Fig 12: Releasing Central Bolts On Intake And Exhaust Camshaft Adjusters

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

Tightening torque: 11 31 5AZ .

Fig 13: Releasing Bearing Journal From Timing Chain Module On Crankcase

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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: Graphic N52.

Fig 14: Releasing Bolts From Timing Chain Module On Cylinder Head

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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 15: 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 sprocket (2) in this position.

Installation note:

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

Fig 16: Installing Timing Chain And Sprocket

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Insert central bolt (1) with hub for crankshaft.

Tighten down central bolt (1).

Tightening torque: 11 21 1AZ .

Install INTAKE AND EXHAUST CAMSHAFT ADJUSTERS .

Install CHAIN TENSIONER .

Fig 17: Inserting Central Bolt With Hub For Crankshaft

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Crank engine twice.

Check TIMING .

If necessary, adjust VALVE TIMING .

Replace front CRANKSHAFT SEAL .

Assemble engine.