Crankshaft: Service and Repair

11 21 500 - Replacing crankshaft (N52)





Special tools required:
- 00 2 510 00 2 510 Dial Gauge with Feeler
- 00 9 120 00 9 120 Torque Angle Measuring Dial
- 11 4 370 11 4 370 Device
- 11 4 440 11 4 440 Engine Support Plate
- 11 9 360 11 9 360 Mandrel






Important!
Aluminium-magnesium materials.

No steel screws/bolts may be used due to the threat of electrochemical corrosion.

A magnesium crankcase requires aluminium screws/bolts exclusively.

Aluminium screws/bolts must be replaced each time they are released.

Aluminium screws/bolts are permitted with and without

colour coding (blue).

For reliable identification:

Aluminium screws/bolts are not magnetic.

Jointing torque and angle of rotation must be observed without fail (risk of damage).





Necessary preliminary tasks:
- Remove engine Removing and Installing Engine.
- Mount engine on assembly stand 11 00 ... Mounting Engine on Assembly Stand.
- Remove vibration damper Service and Repair.
- Removing oil sump. Service and Repair
- Remove oil pump 11 41 000 Removing and Installing/Replacing Oil Pump.
- Remove triangular drive 11 41 010 Removing and Installing/Replacing Chain Module For Oil Pump/Vacuum Pump for oil pump.
- Remove timing chain module Service and Repair.
- Remove cylinder head Removal and Replacement.
- Remove flywheel.
- Remove all pistons Service and Repair.





Release screws (1).

Tightening torque: 11 13 5AZ .

Installation Note:
Replace aluminium screws.

Remove oil deflector (2).





Release screws (1).

Tightening torque: 11 11 2AZ.

Release screws (2).

Tightening torque: 11 11 3AZ.

Installation Note:
Replace aluminium screws.





Release screws (1).

Tightening torque: 11 11 2AZ.

Release screws (2).

Tightening torque: 11 11 4AZ.

Installation Note:
Replace aluminium screws.

Release steel screws (1 to 14) from outside inwards.

Tightening torque: 11 11 1AZ.





Release screws (1).

Tightening torque 11 11 3AZ.

Installation Note:
Replace aluminium screws.

Lift out bedplate.





Remove both radial shaft seals (1).

Note:
Illustrations show N46.





Remove main bearing shells Service and Repair(2 and 3), replace if necessary.

Remove and install crankshaft (1) in direction of arrow.

Important!
Remove crankshaft with aid of a second person.

Weight of crankshaft approx. 23 kg.





Check guide sleeves (1) for damage and correct seating.

Reinstall crankshaft.

Installation Note:
Lubricate all bearing points with engine oil.

Clean all sealing surfaces.

Note:
Illustrations show N46.





Tighten steel screws (1 to 14) from inside outwards.

Tightening torque: 11 11 1AZ.

Tighten screws (2) from inside outwards.

Tightening torque: 11 11 4AZ.

Tighten screws (1).

Tightening torque: 11 11 2AZ.

Installation Note:
Replace aluminium screws.





Tighten aluminium screws exclusively with special tool 00 9 120.

Important!
In the case of aluminium screws, jointing torque and angle of rotation must be observed without fail.





Set up stand with magnetic base on special tool 11 4 440 11 4 440 Engine Support Plate.

Set up special tool 00 2 510 00 2 510 Dial Gauge with Feeler on stand.

Position special tool 00 2 510 00 2 510 Dial Gauge with Feeler on crankshaft.

Move crankshaft in direction of arrow.

Determine bearing play.





Drive in both nozzles (1) with special tool 11 9 360 on left and right into crankcase.

Installation Note:
Always replace nozzles (1).





Installation Note:
Prepare sealing compound (1) in special tool 11 4 370.

Screw on nozzle for injecting sealing compound.

Slowly insert sealing compound (1) with special tool 11 4 370 in direction of arrow.





Replace radial shaft seal at front. Service and Repair

Replace radial shaft seal at rear. Service and Repair

Assemble engine.