1121531 Replacing all crankshaft main bearings (N51)

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2011 BMW 328xi, 2011 BMW 328i, 2010 BMW 328xi, 2010 BMW 328i, and 2009 BMW 328xi. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT: Aluminium-magnesium materials.
No steel screws/bolts may be used due to the threat of electrochemical corrosion.
A magnesium crankcase requires aluminum screws/bolts exclusively.
Aluminum screws/bolts must be replaced each time they are released.
Aluminum screws/bolts are permitted with and without color coding (blue).
For reliable identification:
Aluminum screws/bolts are not magnetic.
Jointing torque and angle of rotation must be observed without fail (risk of damage).

Necessary preliminary tasks:

Remove CRANKSHAFT .

Check setting of oil spray nozzles, adjusting if necessary

Attach special tool 11 4 251 to screw connection on main bearing.

Special tool 11 4 252 must be pre-installed at the seventh main bearing block.

Tightening torque: 11 11 5AZ .

NOTE: See Fig 1.

Fig 1: Attaching Special Tool (11 4 251) To Screw Connection On Main Bearing

Courtesy of BMW OF NORTH AMERICA, INC.

Remove crankshaft (1).

Fig 2: Removing Crankshaft

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: Pilot bearing shell (1) at the fourth bearing block is a thrust bearing.

Fig 3: Identifying Pilot Bearing Shell

Courtesy of BMW OF NORTH AMERICA, INC.

Remove bearing shells (1).

Fig 4: Identifying Bearing Shells

Courtesy of BMW OF NORTH AMERICA, INC.

Installation:

Bearing shell (1) with lubricant groove must be fitted in crankcase upper section.

Bearing shell (2) without lubricant groove must be fitted in crankcase lower section (bedplate).

Fig 5: Identifying Bearing Shells

Courtesy of BMW OF NORTH AMERICA, INC.

Bearing classification (1) on crankcase lower section (values from 1 to 3).

Bearing classification (2) of CONNECTING ROD BEARINGS (b/r).

Fig 6: Identifying Bearing Classifications On Crankcase Lower Section And Connecting Rod Bearings

Courtesy of BMW OF NORTH AMERICA, INC.

Bearing classification (1) in crankcase upper section as per table (values of A/B/C).

Installation:

When all the letters and numbers have been determined, the bearing shell color must be allocated, see table.

IMPORTANT: Engine damage will result if a small bearing play is determined.
The color combination Yellow and Red must not be fitted.
Possible color combinations, see table.

Fig 7: Identifying Bearing Classification On Crankcase Upper Section

Courtesy of BMW OF NORTH AMERICA, INC.

COLOR COMBINATIONS REFERENCE CHART

(A1) Bedplate/Yellow	(B1) Bedplate/Yellow	(C1) Bedplate/Green
(A1) Crankcase/Yellow	(B1) Crankcase/Green	(C1) Crankcase/Green
(A2) Bedplate/Green	(B2) Bedplate/Green	(C2) Bedplate/Green
(A2) Crankcase/Yellow	(B2) Crankcase/Green	(C2) Crankcase/Red
(A3) Bedplate/Green	(B3) Bedplate/Red	(C3) Bedplate/Red
(A3) Crankcase/Green	(B3) Crankcase/Green	(C3) Crankcase/Red

Clean sealing faces (1).

IMPORTANT: Do not clean sealing faces with a metal-cutting tool.

Clean sealing faces (1) with special tool 11 4 470 TOOL .

Fig 8: Identifying Sealing Faces

Courtesy of BMW OF NORTH AMERICA, INC.

Insert all bearing shells (2 and 3).

NOTE: Bearing shell at the fourth bearing block is a thrust bearing.

Fig 9: Identifying Bearing Shells

Courtesy of BMW OF NORTH AMERICA, INC.

Determine bearing play with special tool 00 2 590 .

Fig 10: Checking Bearing Play Using Special Tool (00 2 590)

Courtesy of BMW OF NORTH AMERICA, INC.

Installation:

All measuring points must be free from oil and grease.

Use used screws to determine bearing play.

Set up CRANKCASE LOWER SECTION with bearing shells.

Remove lower crankcase.

Read off bearing play at width of flattened plastic thread and measurement scale.

Crankshaft bearing clearance radial.

Installation:

Remove plastic thread.

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

Fig 11: Locating Bearing Play

Courtesy of BMW OF NORTH AMERICA, INC.

Install CRANKCASE LOWER SECTION .

Assemble engine.