11 21 531 Replacing all crankshaft main bearing shells (N63O1)

Special tools required: 

• 00 2 590
• 00 9 120
• 11 6 251
• 11 6 252

The letters on the crankcase and crankshaft denote the bearing shell classification for the relevant bearing position from 1 to 5 (main bearing cap).

The letters from the crankcase and crankshaft are required to determine the bearing shell colors.

The first letter on the left applies to the first bearing position at the front on the timing chain drive.

The bearing seat (3) is designed as guide bearing.

Necessary preliminary work: 

• Remove CRANKSHAFT 

Fig 1: Identifying Main Bearing Caps

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The letters on the crankcase denote the bearing shell classification for the relevant bearing position from 1 to 5 on the crankcase.

The first letter on the left applies to the first bearing position at the front on the timing chain drive.

Color assignment on crankshaft 1 to 5

Number (3) is a guide bearing.

Fig 2: Identifying Bearing Shell Classification Letters (Main Bearing Cap)

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Observe crankshaft construction stage:

S: Series

B: Repair stage 1

The letters on the crankshaft denote the bearing shell classification for the relevant bearing position from 1 to 5 in the main bearing cap.

The first letter on the left applies to the first bearing position at the front on the timing chain drive.

Color assignment on crankshaft 1 to 5

Number (3) is a guide bearing.

Fig 3: Identifying Guide Bearing Number

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Installation note: 

Install main bearing shells (1) with lubrication groove in crankcase.

Install main bearing shells (2) without lubrication groove in the main bearing caps.

Fig 4: Identifying Bearing Shells With And Without Lubrication Groove

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Fig 5: Identifying Surface For Thrust Washer

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The letters on the crankcase denote the bearing shell classification for the relevant bearing position from 1 to 5 in the crankcase.

The first letter on the left applies to the first bearing position at the front on the timing chain drive.

Fig 6: Identifying Bearing Shell Classification Letters (Main Bearing Cap)

Courtesy of BMW OF NORTH AMERICA, INC.

The letters on the crankshaft denote the bearing shell classification for the relevant bearing position from 1 to 5 in the bearing cap.

The first letter on the left applies to the first bearing position at the front on the timing chain drive.

Example application: 

Bearing Number 1:

Crankcase code letter (Q)  /crankshaft code letter (Q) 

Bearing shell crankcase 1 = green  bearing shell bearing cap 1 = green 

Fig 7: Identifying Crankcase Code Letter

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Bearing Number 2:

Crankcase letter code (H)  /crankshaft letter code (G) 

Bearing shell crankcase 0 = yellow  bearing shell bearing cap 0 = yellow 

Bearing Number 3 (guide bearing): 

Crankcase code letter (I)  /crankshaft code letter (N) 

Bearing shell crankcase 1 = green  bearing shell bearing cap 1 = green 

Bearing Number 4:

Crankcase letter code (H)  /crankshaft letter code (E) 

Bearing shell crankcase 0 = yellow  bearing shell bearing cap 0 = yellow 

Bearing Number 5:

Crankcase letter code (K)  /crankshaft letter code (M) 

Bearing shell crankcase 1 = green  bearing shell bearing cap 1 = green 

Turn back thread support bushing into main bearing cap.

Fig 8: Turning Back Thread Support Bushing Into Main Bearing Cap

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Checking main bearing clearance: 

To check crankshaft bearing play, use the existing main bearing bolts.

Do not twist crankshaft.

Place special tool 00 2 590 (Plastigage model PG 1) onto the oil-free crankshaft (see arrow in illustration).

Fig 9: Placing Plastigage On Oil Free Crankshaft Journal

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Tighten down all collar bolts (M11) of main bearing caps in sequence 1 to 5 to jointing torque.

Tightening torque 11 11 1AZ .

Fig 10: Crankshaft Bolts (M11) Tightening/Loosening Sequence (N63 O1)

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Tighten down all collar bolts (M11) of main bearing caps with special tool 00 9 120 with angle of rotation.

Fig 11: Tightening Collar Bolts Of Main Bearing Caps

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Remove main bearing cap.

Read off main bearing clearance at width of flattened Plastigage with assistance of measurement scale.

Fig 12: Reading Main Bearing Clearance Using Plastigage

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Main bearing play. See N63O1 ENGINE .

• Remove Plastigage
• Apply a coat of oil to new bearing shells and crankshaft

Install CRANKSHAFT .

Secure special tool 11 6 252 with magnetic foot on crankcase.

Position special tool 11 6 251 .

Manually press crankshaft (1) all the way back.

Set dial gauge 11 6 251 to zero.

Manually press crankshaft (1) all the way forward.

Check AXIAL PLAY .

Check guide bearing shell, crankshaft and crankcase if necessary.

Fig 13: Checking Crankshaft Axial Play

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Assemble engine.