11 31 052 Replacing both timing chains (B48, B46)

Special tools required: 

• 2 357 904
• 11 4 120

Necessary preliminary tasks: 

• Remove ENGINE  with transmission
• Remove TRANSMISSION
• Mount engine on ASSEMBLY STAND 
• Remove FLYWHEEL 
• Remove CYLINDER HEAD 
• Remove OIL PUMP 
• Remove REAR TIMING CASE COVER .

Removal: 

Remove drive chain (1) for oil pump.

Fig 1: Drive Chain

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Remove camshaft timing chain (1).

Remove tensioning rail (2) from bearing journal (3).

Fig 2: Camshaft Timing Chain, Tensioning Rail And Bearing Journal

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The crankshaft must be blocked in order to release central bolt (1) of the high pressure pump.

Position crankshaft with guide pin. Secure special tool 2 357 904 with screw (2) in position at the crankcase.

Release central bolt (1).

Fig 3: Securing Special Tool (2 357 904) With Screw At Crankcase

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Use screwdriver (2) to press piston (3) for chain tensioner to limit position and secure piston with special tool 11 4 120 .

Release screws (1). Remove chain tensioner.

Fig 4: Pressing Piston For Chain Tensioner Using Screwdriver

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Undo both bearing journals (1).

Remove guide rail (2).

Release bearing journal (4).

Remove tensioning rail (3).

Fig 5: Guide Rail, Bearing Journal And Tensioning Rail

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Release screw (1) and remove camshaft sprocket (2).

Fig 6: Camshaft Sprocket And Screw

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Release screw (2) and remove special tool 2 357 904 .

Remove timing chain (1).

Fig 7: Removing Special Tool (2 357 904)

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Installation: 

Fit timing chain (1).

Position crankshaft with special tool 2 357 904 .

Secure special tool 2 357 904 with screw (2) in position at the crankcase.

Fig 8: Removing Special Tool (2 357 904)

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Attention  !

Clean all the threads of the bearing journals (if necessary with screw tap).

Install camshaft sprocket and tighten screw until it makes contact.

Position guide rail (2).

Fig 9: Guide Rail, Bearing Journal And Tensioning Rail

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Screw in both bearing journals (1).

Tightening torque: 11 11 3AZ .

Position tensioning rail (3).

Screw in bearing journals (4).

Tightening torque: 11 11 3AZ .

Attention  !

Clean sealing surfaces (1) with compressed air.

Fig 10: Sealing Surfaces

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Install hydraulic chain tensioner. Tighten down screws (1).

Tightening torque: 11 11 7AZ .

Secure piston (3) for chain tensioner with screwdriver (2).

Remove special tool 11 4 120 and slowly remove screwdriver (2).

Fig 11: Pressing Piston For Chain Tensioner Using Screwdriver

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Tighten down central bolt (1).

Tightening torque: 11 11 4AZ .

Fig 12: Securing Special Tool (2 357 904) With Screw At Crankcase

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Install tensioning rail (2) with timing chain (1) for camshafts.

Fig 13: Camshaft Timing Chain, Tensioning Rail And Bearing Journal

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Mount drive chain (1) for oil pump on crankshaft.

Fig 14: Drive Chain

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