Crankshaft Main Bearing: Service and Repair

11 21 531 - Replacing all main crankshaft bearing shells (M57T2)





Special tools required:
- 00 2 590 00 2 590 Measurement Aid
- 00 9 120 00 9 120 Torque Angle Measuring Dial






Necessary preliminary tasks:
- Remove engine
- Remove cylinder head Removal and Replacement
- Remove timing case Service and Repair at front
- Remove radial shaft seal at rear
- Remove oil pump Service and Repair





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





Important!
Check grinding size of crankshaft.





Installation Note:
When exchanging bearing shells (also exchange crankshafts), classification of bearing shell allocation in the crankcase is discontinued.
Only fit yellow bearing shells into the crankcase.





Note:
The axial guide on the crankshaft is fitted to bearing point 6.
Insert pilot bearing shell in the engine block.





The crankshaft is marked with yellow, green or white paint, depending on the tolerance of the main bearing spigot.






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





The bearing shells are marked with yellow, green or white paint.
1. Bearing shell
2. Guide bearing
Observe grinding stage of main bearing journals.






Note:
Main bearing caps 1 to 5 are marked on exhaust side.
The main bearing caps 6 and 7 are not marked.
Main bearing cap 6 is a guide bearing.





Check clearance on main crankshaft bearing.
Install crankshaft, fit special tool 00 2 590 (Plastigage Type PG1) on the oil-free crankshaft.
Do not twist crankshaft.





Install main bearing cap so that grooves in main bearing shell guide are on one side.
Align main bearing cap flush with side of bearing seat.

Note:
To check main bearing clearance, use the old main bearing screws.
Wash and oil main bearing bolts.





Tightening specifications for main bearing:
1. Tighten screws to torque.
2. Tighten down bolts with special tool 00 9 120 to angle of rotation.
Tightening torque, 11 11 1AZ. Specifications





Remove main bearing cap and read off bearing play at width of flattened plastic thread (Plastigage) with assistance of measurement scale.
If necessary, to correct bearing clearance, fit new bearing shells with a different colour coding.





Summary:
Colour code/shaft diameter/bearing strength
- Ge = yellow
- Gn = green
- Ws = white
1. Crankshaft
2. Bearing clearance
3. Bearing shells: Yellow, green, white
4. Bearing cover






Note:
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 on one side.

Align main bearing cap flush with side of bearing seat.





Tightening specifications for main bearing:
1. Tighten all screws on main bearing cover with jointing torque.
2. Unfasten screws on main bearing cover 4.
3. Strike back and front of crankshaft with plastic hammer to centre guide bearing (do not damage crankshaft).
4. Tighten screws of main bearing cover 4 with jointing torque.
5. Tighten down all screws on main bearing caps with special tool 00 9 120 to angle of rotation.
Tightening torque, 11 21 1AZ. Specifications





Check axial play.
If necessary, check guide bearing shells, crankshaft and engine block.





Assemble engine.