11 21 531 Replacing all crankshaft main bearings (N55)

Special tools required: 

• 00 2 590
• 11 4 470
• 11 8 510

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: Inserting Special Tool Into Main Bearing Screw Connection And Securing With Screw

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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.

Fig 3: Identifying Bearing Shell With Lubrication Groove And Bearing Shell Without Lubrication Groove

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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: 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 Code Letters And Star

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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.

Fig 6: Identifying Code Numbers And Letters

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Observe BEARING CLASSIFICATION .

Installation note: 

The letter/number combination produces a bearing shell pairing.

Identification by different colors.

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 With Lubrication Groove And Bearing Shell Without Lubrication Groove

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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 With Lubrication Groove And Bearing Shell Without Lubrication Groove

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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.

Observe BEARING CLASSIFICATION .

Fig 9: Identifying Guide Bearing Shell At Bearing Seat 4

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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 MAIN BEARING JOURNAL 1 , MAIN BEARING JOURNALS 2, 3, 4, 5, 6 , and MAIN BEARING JOURNAL 7 .

Installation note: 

Remove Plastigage.

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

Fig 11: Determining Radial Clearance

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Fit CRANKCASE LOWER SECTION .

Assemble engine.