11 21 531 Replacing all main crankshaft bearing shells (M52 / S52 / M52TU / M54 / M56)

Special tools required:

00 2 590
00 9 120
11 2 110

(engine dismantled)

M52 B20 / M52TU B20

M54 M22

NOTE: Injection nozzles for cooling the pistons are installed in the bores of bearing seats 2 to 7.

Fig 1: Identifying Injection Nozzles For Cooling Pistons

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M52 B25 / B28

S52

M52TU B25 / B28

M54 B25 / B30

M56

NOTE: Injection nozzles for cooling the pistons are installed on the underside of the cylinder between the bearing seats.

Fig 2: Securing Adhesive

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Installation:

Screw threads are coated with screw securing adhesive (Loctite).

Replace screws.

IMPORTANT: Observe grinding stage of crankshaft.

Fig 3: Identifying Crankshaft

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Installation:

When replacing the bearing shells (also for replacement crankshaft), classification for bearing shell arrangement in engine block is waived.

Insert bearing shells with yellow color coding in engine block.

Fig 4: Inserting Bearing Shells With Yellow Color Coding In Engine Block

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NOTE:

Install bearing shells with continuous lubricant groove and one retaining lug in engine block.
Fit bearing shells without continuous lubricant groove and two retaining lugs in bearing cover.

Fig 5: Installing Bearing Shells

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NOTE: The axial guide on the crankshaft is fitted to bearing point 6.

Insert pilot bearing shell in the engine block.

Fig 6: Inserting Pilot Bearing Shell In Engine Block

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Install crankshaft.

NOTE: The crankshaft is marked with yellow, green or white paint according to the tolerance of the main journal.

Fig 7: Identifying Crankshaft

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Installation:

The bearing shell classification for the bearing cover is marked on the crankshaft in yellow, green or white paint.

Insert main bearing shells with same crankshaft color coding in main bearing caps.

Fig 8: Inserting Main Bearing Shells

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The bearing shells are marked with yellow, green or white paint.

Bearing shell
Guide bearing

Observe grinding stage of main bearing journals.

Fig 9: Identifying Bearing Shell & Guide Bearing

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NOTE: Bearing caps 1 to 5 are marked on exhaust side.
Bearing caps 6 and 7 are not designated.
Bearing cap 6 is a thrust bearing.

Fig 10: Identifying Bearing Cap

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Check clearance on main crankshaft bearing.

Install crankshaft and place special tool 00 2 590 (Plastigage Type PG1) on oil-free crankshaft.

Do not twist crankshaft.

Fig 11: Checking Clearance On Main Crankshaft Bearing

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Install main bearing cap so that grooves in main bearing shell guide are one side.

Align main bearing cap flush with side of bearing seat.

Fig 12: Installing Main Bearing Cap

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Installation:

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

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

Tighten down main bearing screws with jointing torque.
Tighten down main bearing bolts with special tool 00 9 120 to angle of rotation.

Tightening torque. Refer to ENGINE - TIGHTENING TORQUES - 3-SERIES (E46) .

Fig 13: Tightening Down Main Bearing Screws With Jointing Torque

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Remove main bearing cap and read off bearing clearance at width of pinched plastic thread on measuring scale.

Radial crankshaft bearing clearance.

If necessary, to correct bearing clearance, fit new bearing shells with a different color coding.

Fig 14: Removing Main Bearing Cap

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Remove plastic thread.

Coat main bearing shells and crankshaft with engine oil.

Install main bearing cap so that grooves in main bearing shell guide are one side.

Align main bearing cap flush with side of bearing seat.

Fig 15: Aligning Main Bearing Cap Flush With Side Of Bearing Seat

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Installation:

Always replace bolts of main bearing cap with new bolts.

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

NOTE: The reinforcement plates are not fitted on engines with gray cast iron engine blocks or on engines with oil pumps integrated in oil scrapers.

Installation:

Install reinforcement plates and fit screws with zero backlash.

Install main bearing shells and abut firmly.

Tighten down screw connection on reinforcement plates.

Fig 16: Installing Main Bearing Shells & Abut Firmly

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Tightening specifications for main bearing:

Tighten all screws on main bearing cover with jointing torque.
Unfasten screws on main bearing cover 6.
Strike back and front of crankshaft with plastic hammer to center thrust bearing (do not damage crankshaft).
Tighten screws of main bearing cover 6 with jointing torque.
Tighten down all screws of main bearing caps with special tool 11 2 110 or with special tool 00 9 120 to torsion angle.
Tightening torque. Refer to ENGINE - TIGHTENING TORQUES - 3-SERIES (E46) .

Fig 17: Tightening Specifications For Main Bearing

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Check axial play.

If permitted end float is exceeded, check crankshaft, guide bearing shells and engine block, replacing if necessary, end float.

Fig 18: Checking Axial Play

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