11 21 531 Replacing all crankshaft main bearings (N54)

Special tools required:

IMPORTANT: Aluminium screws/bolts must be replaced each time they are released.
Aluminium screws/bolts are permitted with and without color coding (blue).
For reliable identification:
Aluminium screws/bolts are not magnetic .
Jointing torque and angle of rotation must be observed without fail (risk of damage).

Necessary preliminary tasks:

Remove CRANKSHAFT

Check setting of oil spray nozzles, adjusting if necessary:

Attach special tool 11 8 510 to main bearing screw connection, secure with bolt (1).

Fig 1: Checking Position Of Oil Spray Nozzles

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Installation note:

The oil nozzle must be located precisely in the groove of special tool 11 8 510 .

If necessary, adjust oil nozzle.

Adjust oil nozzle.

Release screw (1).

Tightening torque 11 11 5AZ .

Fig 2: Identifying Banjo Bolt

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Remove bearing shells (2) and (3).

NOTE: Guide bearing shell (3) is a thrust bearing.

Observe BEARING CLASSIFICATION .

Fig 3: Identifying Bearing Shells

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Installation note:

Bearing shell (1) with lubricant groove must be fitted in crankcase upper section.

Bearing shell (2) without lubricant groove must be fitted in crankcase lower section (bedplate).

Fig 4: Identifying Bearing Shell With/Without Lubricant Groove

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IMPORTANT: Allocation of bearing positions:
Bearing position 1 is at the front on the timing chain drive in the direction of travel.

Main bearing classification (1) for crankcase lower half (bedplate), code numbers 1 2 3, see MAIN BEARING CLASSIFICATION .

Observe BEARING CLASSIFICATION .

Bearing classification (2) of CONNECTING RODS code letters b and r.

Fig 5: Identifying Bearing Classifications

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Main bearing classification (1) in crankcase, code letters A/B or C, see MAIN BEARING CLASSIFICATION .

Installation note:

When all the letters and number code have been determined, the bearing shell color must be allocated.

Fig 6: Identifying Main Bearing Classification In Crankcase

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Installation note:

The letter/number combination produces a bearing shell pairing.

Identification by different colors.

IMPORTANT: First bearing position is on the timing drive.
The color combination Yellow and Red must not be fitted.
Engine damage will result if excessively small bearing play is determined.

Code letters on crankcase:

Code letter A = bearing shell (1) color Yellow.

Code letter B = bearing shell (1) color Green.

Code letter C = bearing shell (1) color Red.

Code numbers on crankshaft:

Code number 1 = bearing shell (2) Yellow.

Code number 2 = bearing shell (2) Green.

Code number 3 = bearing shell (2) Red.

Fig 7: Identifying Bearing Shell With/Without Lubricant Groove

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IMPORTANT: The color combination Yellow and Red must not be fitted; the bearing colors Green/Green must be selected for this color combination, see MAIN BEARING CLASSIFICATION .

Installation example:

For bearing 1 with code letter A on the crankcase and code number 1 on the crankshaft bearing shell (1) with the color Yellow is required for the crankcase and bearing shell (2) with the color Yellow for the crankcase lower half (bedplate).

Bearing 2: A and 2 colors Yellow and Green.

Fig 8: Identifying Bearing Shell With/Without Lubricant Groove

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Bearing 3: B and 2 colors Green and Green.

Bearing 4: C and 2 colors Red and Green.

Bearing 5: B and 1 colors Green and Yellow.

Bearing 6: C and 3 colors Red and Red.

Bearing 7: C and 1 colors Green and Green.

The color combination Yellow and Red must not be fitted.

Installation note:

Possible color combinations for mounting the crankshaft in the crankcase.

MAIN BEARING CLASSIFICATION

(A 1) Crankcase/Yellow	(B 1) Crankcase/Green	(C 1) Crankcase/Green
(A 1) Crankcase lower half/Yellow	(B 1) Crankcase lower half/Yellow	(C 1) Crankcase lower half/Green

(A 2) Crankcase/Yellow	(B 2) Crankcase/Green	(C 2) Crankcase/Red
(A 2) Crankcase lower half/Green	(B 2) Crankcase lower half/Green	(C 2) Crankcase lower half/Green

(A 3) Crankcase/Green	(B 3) Crankcase/Green	(C 3) Crankcase/Red
(A 3) Crankcase lower half/Green	(B 3) Crankcase lower half/Red	(C 3) Crankcase lower half/Red

Insert all bearing shells (2 and 3).

IMPORTANT: Clean sealing surfaces.
Do not clean sealing faces with a metal-cutting tool.

Only use special tool 11 4 470 to clean sealing surfaces.

Determine bearing play with special tool 00 2 590 .

Installation note:

All measuring points must be free from oil and grease.

Use used screws to determine bearing play.

Fig 9: Identifying Bearing Shells

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Set up crankcase lower section (bedplate) with bearing shells.

Remove crankcase

lower section (bedplate).

Read off BEARING PLAY at width of flattened plastic thread and measurement scale.

Installation note:

Remove Plastigage.

Apply a light coat of oil to bearing shells and crankshaft.

Fig 10: Checking Radial Clearance At Width Of Flattened Plastic Thread (Plastigage)

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Install crankcase lower section (bedplate).

Assemble engine.