11 21 531 Replacing Crankshaft Main Bearing Shells N73)

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NOTE:

For Special Tool identification, see MAINTENANCE AND GENERAL INFORMATION - SPECIAL TOOLS .

Special Tools Required:

00 2 590
00 9 120

IMPORTANT: Replace main bearing screws. Do not wash off bolt coating. There must be no oil in the blind holes (risk of cracking ).

Necessary Preliminary Tasks:

Remove engine. Refer to 11 00 050 REMOVING AND INSTALLING ENGINE (N73) .
Remove left cylinder head. Refer to 11 12 105 REMOVING AND INSTALLING LEFT CYLINDER HEAD (N73) .
Remove right cylinder head. Refer to 11 12 106 REMOVING AND INSTALLING RIGHT CYLINDER HEAD (N73) .
Remove hub for vibration damper. Refer to 11 23 031 REMOVING AND INSTALLING/REPLACING VIBRATION DAMPER HUB (N73) .
Remove lower timing case cover. Refer to 11 14 110 REMOVING AND INSTALLING LOWER TIMING CASE COVER (N73) .
Remove rear timing case cover.
Remove upper oil sump. Refer to 11 13 010 REMOVING AND INSTALLING/REPLACING OIL SUMP TOP SECTION (N73) .
Remove oil pump. Refer to 11 41 000 REMOVING AND INSTALLING/REPLACING OIL PUMP (N73) .
Remove flywheel. Refer to 11 22 510 REMOVING AND INSTALLING/REPLACING FLYWHEEL (N73) .
Remove all pistons. Refer to 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.

Fig 1: Releasing Thread Support Bushings From Main Bearing Caps

Courtesy of BMW OF NORTH AMERICA, INC.

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

Lift out crankshaft (2).

Fig 2: Locating Guide Bearing

Courtesy of BMW OF NORTH AMERICA, INC.

Unscrew thread support bushings in main bearing caps.

Fig 3: Releasing Thread Support Bushings In Main Bearing Caps

Courtesy of BMW OF NORTH AMERICA, INC.

Installation:

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 Types Of Main Bearing Shells

Courtesy of BMW OF NORTH AMERICA, INC.

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.

Fig 5: Locating Bearing Shell With Lubricating Groove In Crankcase

Courtesy of BMW OF NORTH AMERICA, INC.

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.

Fig 6: Identifying Special Tool 00 2 590

Courtesy of BMW OF NORTH AMERICA, INC.

Tighten all screws on main bearing cover with jointing torque.
Tighten down all screws on main bearing caps with special tool 00 9 120 to torsion angle.

Installation:

Tightening torque, refer to 11 11 2AZ in ENGINE - TIGHTENING TORQUES .

Fig 7: Tightening Main Bearing Caps Screws

Courtesy of BMW OF NORTH AMERICA, INC.

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 ).

Fig 8: View Of Plastigage

Courtesy of BMW OF NORTH AMERICA, INC.

Tightening specifications for main bearing:

Tighten all bolts on main bearing cover to jointing torque.
Release bolt on main bearing cap 7.
Strike back and front of crankshaft with plastic hammer to center thrust bearing (do not damage crankshaft).
Check axial play.
Tighten bolts of main bearing cap no. 7 to jointing torque.
Tightening torque, refer to 11 11 2AZ in ENGINE - TIGHTENING TORQUES .

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.

Tightening torque, refer to 11 11 2AZ in ENGINE - TIGHTENING TORQUES .

Installation:

Tighten down thread support bushing (2).

Tightening torque, refer to 11 11 3AZ in ENGINE - TIGHTENING TORQUES .

Installation:

Replace flanged head screws (1) and tighten down.

Tightening torque, refer to 11 11 3AZ in ENGINE - TIGHTENING TORQUES .

Fig 10: Locating Main Bearing Bolts

Courtesy of BMW OF NORTH AMERICA, INC.

Install engine in reverse sequence to its removal.

Installation:

Replace all big-end bearings and main bearing shells.