11 21 531 Replacing all crankshaft main bearing shells (N20, N26)

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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 2 212 829 .

Insert special tool 2 212 829 into main bearing screw connection and secure from turning with screw (1).

Secure oil spray nozzle with screw (2).

Tightening torque: 11 11 3AZ .

Fig 1: Inserting Special Tool (2 212 829) Into Main Bearing Screw Connection

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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 2: Bearing Shell With/Without Lubricant Groove

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Main bearing classification:

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

Code letter (K) stands for clutch side.

Same procedure, with missing code letter (K).

The bearing seat assignment is from 5 to 1, the first bearing position is at the control drive.

Fig 3: Crankcase Upper Section Code Letters

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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 5, the first bearing position is located on timing drive.

Fig 4: Crankcase Lower Section Code Letters

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NOTE: Code letters (2) are required exclusively for classifying CONNECTING ROD BEARING .
Observe bearing classification. See N20/N26 ENGINES .

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) in blue with lubricating groove.

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

Fig 5: Bearing Shell With/Without Lubricant Groove

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Code numbers on crankshaft:

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

ID code 2 = Bearing shell (2) in blue without lubricating groove.

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

IMPORTANT: The color set yellow and red must not be installed, bearing colors blue/blue must be selected for this color set.

Installation note:

Possible color combinations for mounting the crankshaft in the crankcase.

Fig 6: Bearing Shell With/Without Lubricant Groove

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Installation example:

For bearing 1 with the code letter C at the crankcase and the ID code 2 on the crankshaft , the bearing shell (1) in red is required for the top part of the crankcase and a bearing shell (2) in blue is required for the crankcase lower section (bedplate).

Bearing 2: A and 2 in yellow and blue.

Bearing 3: C and 2 in red and blue.

Bearing 4: A and 1 colors Yellow and Yellow.

Bearing 5: C and 1 in blue and blue.

IMPORTANT: The color set yellow and red must not be installed, bearing colors blue/blue must be selected for this color set.

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

NOTE: Guide bearing shell (1) at bearing seat 3 is a thrust bearing.

Fig 7: Guide 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.

Fig 8: Installing Bearing Shells And Guide Bearing Shell

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

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.

Installation note:

Remove Plastigage.

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

Fig 9: Checking Radial Clearance At Width Of Flattened Plastic Thread (Plastigage)

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Fit CRANKCASE LOWER SECTION .

Assemble engine.