11 21 531 Replacing all crankshaft main bearings (N55)

Special tools required:

Necessary preliminary tasks

Remove CRANKSHAFT .

Checking position of oil spray nozzles

Check position of oil spray nozzle according to position on special tool 11 8 510 .

Insert special tool 11 8 510 into main bearing screw connection and secure from turning with screw (1).

Fig 1: Inserting Special Tool (11 8 510) Into Main Bearing

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If necessary, adjust oil spray nozzles and secure.

Tighten banjo bolt (1).

Tightening torque: 11 11 5AZ .

Fig 2: Identifying Oil Spray Nozzles Banjo Bolt

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Installation note:

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

Bearing shell (2) without lubricating groove must be installed in lower section of crankcase.

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

Fig 3: Identifying Bearing Shell

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Main bearing classification (1) in crankcase.

Installation note:

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

Fig 4: Identifying Crankcase Main Bearing Classification

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Main bearing classification

Code letters A/B or C) are used for the crankcase upper section.

For bearing seat assignment from 1 to 7, the first bearing position is indicated by a star (1) on timing drive.

Fig 5: Identifying Crankcase Upper Section Codes

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Main bearing classification

ID codes 1/2 or 3) are used for crankcase lower section.

For bearing seat assignment (1) from 1 to 7, the first bearing position is located on timing drive.

NOTE: Code letters (2) are required exclusively for classifying CONNECTING ROD BEARING .

Observe bearing classification. See ENGINE - TECHNICAL DATA - E92 .

Fig 6: Identifying Crankcase Lower Section Codes

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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.
Engine damage will result if an insufficiently small radial clearance is determined.
If a large radial clearance is determined, this can lead to noises in crankshaft drive.

Code letters on crankcase

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

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

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

Code numbers on crankshaft:

Code number 1 = bearing shell (2) Yellow without lubricating groove.

Code number 2 = bearing shell (2) Green without lubricating groove.

Code number 3 = bearing shell (2) Red without lubricating groove.

Fig 7: Identifying Bearing Shell

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IMPORTANT: The color set Yellow and Red must not be fitted; the bearing colors Green/Green must be selected for this color set.

Installation note:

Possible color combinations for mounting the crankshaft in the crankcase.

Installation example

For bearing 1 with code letter B on crankcase and code letter 1 on crankshaft , the bearing shell (1) with the color Green is required for the crankcase upper section and bearing shell (2) with the color Yellow for the crankcase lower section (bedplate).

Fig 8: Identifying Bearing Shell

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Bearing 2: B and 2 colors Green and Green.

Bearing 3: A and 2 colors Yellow and Green.

Bearing 4: B and 2 colors Green and Green.

Bearing 5: A and 1 colors Yellow and Yellow.

Bearing 6: B and 3 colors Green and Red.

Bearing 7: B and 1 colors Green and Yellow.

IMPORTANT: The color set Yellow and Red must not be fitted; the bearing colors Green/Green must be selected for this color set.

(A 1) Crankcase/Yellow	(B 1) Crankcase/Green	(C 1) Crankcase/Green
(A 1) Crankcase lower section/Yellow	(B 1) Crankcase lower section/Yellow	(C 1) Crankcase lower section/Green
(A 2) Crankcase/Yellow	(B 2) Crankcase/Green	(C 2) Crankcase/Red
(A 2) Crankcase lower section/Green	(B 2) Crankcase lower section/Green	(C 2) Crankcase lower section/Green
(A 3) Crankcase/Green	(B 3) Crankcase/Green	(C 3) Crankcase/Red
(A 3) Crankcase lower sections/Green	(B 3) Crankcase lower section/Red	(C 3) Crankcase lower section/Red

NOTE: Guide bearing shell (1) at bearing seat 4 is a thrust bearing.

Observe bearing classification . See 1121 CRANKSHAFT AND BEARINGS (N55) .

Fig 9: Locating Bearing Shell

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IMPORTANT: Do not use any metal-cutting tools.
Only use special tool 11 4 470 to clean sealing surfaces.

Installation note:

Clean all sealing surfaces.

Install bearing shells (2) and guide bearing shell (3).

Fig 10: Installing Bearing Shells And Guide Bearing Shell

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Installation note:

If a radial clearance needs to be redetermined, use special tool 00 2 590 to do this.

Installation note:

All measuring points must be clean and free from oil and grease. If necessary, clean all measuring points.

The old bearing screws can be used to determine the radial clearance.

Set up CRANKCASE LOWER SECTION with bearing shells.

Remove crankcase lower section.

Read off radial clearance . See 1121 CRANKSHAFT AND BEARINGS (N55) at width of flattened Plastigage and measuring scale.

Installation note:

Remove Plastigage.

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

Fig 11: Locating Bearing Shells And Crankshaft Oil Coat

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Fit CRANKCASE LOWER SECTION .

Assemble engine.