Crankshaft Main Bearing: Service and Repair

11 21 531 - Replacing all main crankshaft bearing shells (N62/N62TU)





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





Necessary preliminary tasks:
- (engine dismantled)
- Clean components before installing.
- Preparatory tasks are described in the section Replacing crankshaft Service and Repair.





Note:
Install main bearing shells (1) with lubrication groove in crankcase.
Install main bearing shells (2) without lubrication groove in the main bearing caps.





The letter (1) denotes the crankshaft construction stage.
S= Series
B= Construction stage 1
C= Construction stage 2
The numbers (2) denote the bearing shell classification for the relevant bearing position from 1 to 5 (main bearing cap).
1= yellow
2= green
3= violet





The letters (1) denote the bearing shell classification for the relevant bearing position from 1 to 5 in the crankcase and is located on the transmission side in the Vee. The first letter on the left applies to the first bearing position at the front.
Y= yellow
G= green
V= violet





Note:
Main bearing caps (1, 2 and 3) are identified with punch numbers.
Main bearing caps (4 and 5) are not identified.





Note:
Main bearing cap number 5 can be identified by the surfaces (1) for the stop disks of the thrust bearing.





Unscrew thread support bushings in main bearing caps.





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.
Fit special tool 00 2 590 (Plastigage Type PG 1) to the oil-free crankshaft.





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 00 9 120 Torque Angle Measuring Dial and torsion angle.
Tightening torque, 11 11 2AZ 11 11 Engine Block.





Remove main bearing cap.
Read off main bearing play at width of flattened plastic thread with assistance of measurement scale.
Main bearing play.
- Remove plastic thread.
- Lubricate bearing shells and bearing shells.





Note:
Always replace main bearing bolts of main bearing caps with new bolts.
Do not wash off bolt coating.
No oil is permitted in the blind bores! (Danger of cracking).





Tightening specifications for main bearing:
1. Tighten all screws on main bearing cover with jointing torque.
2. Unfasten screws on main bearing cover 5.
3. Strike back and front of crankshaft with plastic hammer to center thrust bearing (do not damage crankshaft).
Check axial play.
Check guide bearing shell, crankshaft and crankcase if necessary.
4. Tighten screws of main bearing cover 5 with jointing torque.
5. Tightening torque 11 11 2AZ 11 11 Engine Block.





Tighten down all screws on main bearing caps with special tool 00 9 120 00 9 120 Torque Angle Measuring Dial and torsion angle.
Tightening torque, 11 11 2AZ 11 11 Engine Block.
Tighten down thread support bushings (2).
Tightening torque, 11 11 3AZ 11 11 Engine Block.





Replace flanged head screws (1) and tighten down.
Tightening torque, 11 11 3AZ 11 11 Engine Block.