11 21 500 Replacing the crankshaft (N47D20 K/U/O/T 1)

Special tools required:

IMPORTANT: Replace main and connecting rod bolts.
There must be no oil in the blind holes (risk of cracking) .
Do not wash off bolt coating.
Incorrect assembly of the bearing caps will result in damage to the crankcase.
It is necessary to remove the counterbalance shafts (AGW) in order to remove the crankshaft.
To properly adjust the counterbalance shafts, a new, coated intermediate gear must always be fitted.

Necessary preliminary tasks:

Remove ENGINE .
Mount engine on assembly stand. See MOUNTING ENGINE ON ASSEMBLY STAND (N47 D20 O1) .
Remove COOLANT PUMP .
Remove OIL PUMP .
Remove END COVER at rear.
Remove both TIMING CHAINS .
REMOVE ALL PISTONS .

Check crankshaft side clearance.

Fit special tool 11 6 250 .

SIDE CLEARANCE .

If the permitted side clearance is exceeded:

Check crankshaft and guide bearing shells.
Replace worn component.

Fig 1: Checking Crankshaft Side Clearance
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Remove sealing caps (1) with a suitable tool (2).

Installation note:

Replace sealing cap with O-ring.

Fig 2: Removing Sealing Caps With Suitable Tool

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Turn crankshaft until special tool 11 8 750 engages in left counterbalance shaft (1) (see arrow).

NOTE: Figure shows crankshaft removed.

Fig 3: Removing Crankshaft

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Turn crankshaft until special tool 11 8 750 engages in right counterbalance shaft (1).

See arrow.

NOTE: Graphic shows crankshaft removed.

Fig 4: Removing Crankshaft

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NOTE: Picture shows N47.

Special tool 11 8 750 can only be attached to the coolant pump on the crankcase using a bolt (1).

Fig 5: Identifying Special Tool (11 8 750)

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Slacken nut (1).

Tightening torque: 11 27 2AZ .

Undo screws (2 and 3)

Fig 6: Identifying Nut And Screws

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Tightening torque: 11 27 1AZ

Remove nut from intermediate gearwheel (1).

Remove intermediate gearwheel (1).

NOTE: The gear is pressed onto the counterbalance shaft with a taper and can only be released with special tool 11 8 870 .
Once the gear has been released from the counterbalance shaft, special tool 11 8 870 can be unscrewed again by hand.

Fig 7: Identifying Intermediate Gearwheel And Special Tool (11 8 870)

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Screw special tool 11 8 870 into counterbalance shaft gear and release counterbalance shafts from gears.

IMPORTANT: Risk of damage! on crankcase.
Use special tool 00 2 300 to move engine to vertical position.

Remove counterbalance shaft (1) in upward direction of arrow from crankcase (2).

NOTE: Shown with crankshaft removed for clearer illustration.

Fig 8: Removing Counterbalance Shaft

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IMPORTANT: Danger of mixing up needle bearings.
Needle bearings have different diameters.

Release needle bearing (1) in direction of arrow.

Remove released needle bearing (1) from counterbalance shaft (2) in direction of arrow.

Fig 9: Releasing Needle Bearing

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Check counterbalance shaft (2) for wear at the bearing position and replace if necessary.

NOTE: Bearing caps (1) 1...5 are marked on the exhaust side.
Bearing cap 3 is installed as a thrust bearing.

NOTE: Illustration shows bearing seat number 5.

Fig 10: Identifying Bearing Caps Mark

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Release main bearing screw connection of main bearing cap (1).

Remove main bearing cap 1...5.

IMPORTANT: With the assistance of a second person, remove crankshaft and carefully place to one side.
Pay attention to oil hole in bearing shell.
Pay attention to installation position of CRANKSHAFT MAIN BEARING SHELLS .

Fig 11: Identifying Main Bearing Cap

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Coat bearing shells with oil.

Install crankshaft.

Fit bearing caps 1 to 5 so that the ID codes always point to the exhaust side.

Both locating grooves of bearing shells in crankcase and on bearing cap must be mounted on one side.

IMPORTANT: Do not fit bearing cap in incorrect position.
Risk of damage to molding on crankcase.

Fig 12: Identifying Bearing Caps

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Align bearing cap exactly.

Fit main bearing bolts.

Tighten main bearing bolts in sequence (1 to 10) (observe tightening specifications).

Tightening torque: 11 11 1AZ .

Fig 13: Main Bearing Cap Bolts Tightening/Loosening Sequence (N47 D20 O1)

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IMPORTANT: The crankshaft must be fixed in the BDC position of cylinder No. 1 in order to adjust the counterbalance shafts.

Position special tool 11 8 791 on crankcase and secure with special tool 11 8 793 .

Fig 14: Positioning Special Tool (11 8 791) On Crankcase

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Secure crankshaft with knurled screw 11 8 792 on special tool 11 8 791 .

Use special tool 00 2 300 to move engine to vertical position.

Fig 15: Securing Crankshaft On Special Tool (11 8 791)

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Schematic representation of the differential bevel and intermediate gears.

IMPORTANT: To adjust the counterbalance shafts, it is essential to fit a new coated intermediate gearwheel (2).

All marks on the drive gears (1 and 3) and intermediate gearwheel (2) must point vertically to the oil sump sealing surface (upwards).

Fig 16: Identifying Marks On Drive Gears And Intermediate Gearwheel

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Installation note:

To facilitate installation of counterbalance shafts, rotate engine with special tool 00 2 300 to a convenient working position.

Fit gear (1) for right counterbalance shaft in direction of arrow.

Marks on drive gear counterbalance shaft (1) must point vertically to oil sump sealing surface (upwards).

NOTE: Shown with crankshaft removed for clearer illustration.

Fig 17: Installing Gear

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IMPORTANT: Risk of mixing up gears.
Pay attention to inclination of tooth flanks.

Fit gear (1) for left counterbalance shaft in direction of arrow.

Marking on drive gear (1) must point vertically to oil pan sealing surface (upwards).

NOTE: Shown with crankshaft removed for clearer illustration.

IMPORTANT: Risk of mixing up gears.
Pay attention to inclination of tooth flanks.

Fig 18: Installing Gear

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Insert counterbalance shafts (1) in direction of arrow in crankcase (2).

NOTE: Shown with crankshaft removed for clearer illustration.

Fig 19: Inserting Counterbalance Shaft

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IMPORTANT: Do not drop counterbalance shafts into the bearing positions.

Insert special tool 64 1 020 or a suitable tool through the gear into the counterbalance shaft.

Carefully insert counterbalance shaft (1) into gear in direction of arrow.

Fig 20: Inserting Special Tool (64 1 020)

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Position counterbalance shaft (1) in direction of arrow in gear (2).

NOTE: Shown with crankshaft removed for clearer illustration.

Fig 21: Positioning Counterbalance Shaft

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IMPORTANT: Do not drop counterbalance shafts into the bearing positions.

Insert special tool 64 1 020 or a suitable tool through the gear into the counterbalance shaft.

Carefully insert counterbalance shaft (1) into gear in direction of arrow.

Fig 22: Inserting Special Tool (64 1 020)

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Position counterbalance shaft (1) in direction of arrow in gear (2).

NOTE: Shown with crankshaft removed for clearer illustration.

Fig 23: Positioning Counterbalance Shaft

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Screw both bolts (1) into the counterbalance shafts on the left and right.

Do not tighten both bolts otherwise the counterbalance shafts may jam and it will no longer be possible to position them in the next operation.

Fig 24: Identifying Bolts

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Position both counterbalance shafts.

The balance weights of the counterbalance shafts must point to the oil sump. For this purpose, the engine must be moved into the normal position with special tool 00 2 300 .

Both counterbalance shafts together with the balance weights must now face downwards towards the oil sump.

Secure special tool 11 8 750 to the crankcase using the screws (1) for the coolant pump.

Fig 25: Identifying Special Tool (11 8 750)

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Special tool 11 8 750 can only be attached to the coolant pump on the crankcase using a bolt (1).

NOTE: Picture shows N47.

Schematic representation of the differential bevel and intermediate gears.

All marks on the drive gears (1 and 3) and intermediate gearwheel (2) must point vertically to the oil sump sealing surface (upwards).

Fig 26: Identifying Marks On Drive Gears And Intermediate Gearwheel

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Installation note:

The gear must be loose on the right-hand counterbalance shaft otherwise it will not be possible to install the intermediate gearwheel.

Install new intermediate gearwheel with coating.

Install intermediate gearwheel.

Secure bolt for counterbalance shafts (2 and 3) using special tool 00 9 120 .

Tightening torque: 11 27 1AZ .

Fig 27: Identifying Nut And Screws

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IMPORTANT: Before the intermediate gear (2) is secured, the intermediate gear (2) must be pressed hand-tight onto the gearing of the crankshaft (4) and counterbalance shaft (3) until zero-lash is achieved in both gears.

Fig 28: Identifying Marks On Drive Gears And Intermediate Gearwheel

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Tighten nut (1).

Tightening torque: 11 27 2AZ .

Fig 29: Identifying Nut And Screws

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Check SIDE CLEARANCE .

Fig 30: Checking Crankshaft Side Clearance

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Assemble engine.