11 21 531 Replacing all crankshaft main bearing (N55)

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Special tools required:

Necessary preliminary work:

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: Checking Oil Spray Nozzles Position Using Special Tool (11 8 510)

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If necessary, adjust oil spray nozzles and secure.

Tighten banjo bolt (1).

Tightening torque: 11 11 5AZ .

Fig 2: Identifying 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 Shells

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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 BEARING SHELL GUIDE .

Fig 4: Locating Main Bearing Classification In Crankcase

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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 the transmission side.

Fig 5: Identifying Main Bearing Code Letters On The Transmission Side

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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 N55 ENGINE .

Fig 6: Identifying Code Numbers And Letters

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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 bearing play is determined.
If a large bearing 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 Shells

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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).

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.

Fig 8: Identifying Bearing Shells

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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.

BEARING SHELL GUIDE

(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 N55-01B1S1 CRANKSHAFT AND BEARINGS , N55-01B1S2 CRANKSHAFT AND BEARINGS and N55-01B1S3 CRANKSHAFT AND BEARINGS .

Fig 9: Identifying Guide Bearing Shell At Bearing Seat 4

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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 at width of flattened Plastigage and measuring scale. See N55-01B1S1 CRANKSHAFT AND BEARINGS , N55-01B1S2 CRANKSHAFT AND BEARINGS and N55-01B1S3 CRANKSHAFT AND BEARINGS .

Fig 11: Reading Crankcase Bearing Radial Clearance Using Plastigage

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Installation note:

Remove Plastigage.

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

Fit CRANKCASE LOWER SECTION .

Assemble engine.