Special tools required:

• 00 2 590. See 00 2 590 PLASTIGAGE (5)
• 00 9 120. See 00 9 120 TORQUE ANGLE MEASURING DIAL

Necessary preliminary tasks: 

• Remove engine. See 11 00 050 Removing and Installing Engine (N73) 
• Remove left cylinder head. See 11 12 105 Removing and Installing Left Cylinder Head (N73) 
• Remove right cylinder head. See 11 12 111 Replacing Right Cylinder Head Gasket (N73) 
• Remove hub for vibration damper. See 11 23 010 Removing and Installing/Replacing Vibration Damper (N73) 
• Remove lower timing case cover. See 11 14 141 Replacing Radial Seal In Lower Timing Case Cover (N73) 
• Remove rear timing case cover.
• Remove upper oil sump. See 11 13 010 Removing and Installing/Replacing Oil Sump Top Section (N73) 
• Remove oil pump. See 11 41 000 Removing and Installing/Replacing Oil Pump (N73) 
• Remove flywheel. See 11 22 510 Removing and Installing/Replacing Flywheel (N73) 
• Remove all pistons. See 11 25 530 Removing and Installing/Replacing All Pistons (N73) 

Release taper screw mount (1) on all main bearing caps.

Release thread support bushings (2) on all main bearing caps.

Release main bearing bolts along lines (3).

Remove main bearing caps 1 to 7.

Main bearing shell (1) on bearing cap number 7 is a guide bearing.

Lift out crankshaft (2).

Unscrew thread support bushings in main bearing caps.

Installation: 

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

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

Bearing shell (1) with lubricating groove in crankcase

Installation: 

The bearing shell classification for the relevant bearing position from 1 to 7 is stamped in the crankcase (2).

Y= yellow

G= green

V= violet

Checking main bearing clearance: 

To check crankshaft bearing clearance, use old main bearing screws.

There must be no oil in the blind holes (risk of cracking).

Do not twist crankshaft.

Place special tool 00 2 590 (Plastigage model PG 1) on oil-free crankshaft. See 00 2 590 PLASTIGAGE (5)

1. Tighten all screws on main bearing cover with jointing torque.
2. Tighten down all screws on main bearing caps with special tool 00 9 120 to torsion angle. See 00 9 120 TORQUE ANGLE MEASURING DIAL

Installation: 

Tightening torque 11 11 2AZ. See 11 11 ENGINE BLOCK

Remove main bearing cap.

Read off main bearing clearance with measuring scale.

Main bearing play.

• Remove plastic thread.
• Lubricate bearing shells and bearing shells.

Installation: 

Always replace main bearing bolts.

Do not wash off bolt coating.

There must be no oil in the blind holes (risk of cracking)  .

Tightening specifications for main bearing:

1. Tighten all bolts on main bearing cover to jointing torque. 
2. Release bolt on main bearing cap 7  .
3. Strike back and front of crankshaft with plastic hammer to center thrust bearing (do not damage crankshaft).

   Check axial play.

4. Tighten bolts of main bearing cap no. 7 to jointing torque.
5. Tightening torque 11 11 2AZ. See 11 11 ENGINE BLOCK
   Fig 9: Checking Axial Play

   Courtesy of BMW OF NORTH AMERICA, INC.

Installation: 

Replace main bearing bolts (3).

Tighten down all bolts of main bearings (3) with special tool 00 9 120. See 00 9 120 TORQUE ANGLE MEASURING DIAL

Tightening torque 11 11 2AZ. See 11 11 ENGINE BLOCK

Installation: 

Tighten down thread support bushing (2).

Tightening torque 11 11 3AZ. See 11 11 ENGINE BLOCK

Installation: 

Replace flanged head screws (1) and tighten down.

Tightening torque 11 11 3AZ. See 11 11 ENGINE BLOCK

Install engine in reverse sequence to its removal.

Installation: 

Replace all big-end bearings and main bearing shells.