Crankshaft Main Bearing: Service and Repair
11 21 531 Replacing all crankshaft main bearings (N54, N54T)Special tools required:
Important!
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 crankshaft
Check setting of oil spray nozzles, adjusting if necessary:
Attach special tool 11 8 510 to main bearing screw connection, secure with bolt (1).
Installation note:
The oil nozzle must be located precisely in the groove of special tool 11 8 510.
If necessary, adjust oil nozzle.
Adjust oil nozzle.
Release screw (1).
Tightening torque 11 11 5AZ.
Remove bearing shells (2) and (3).
Note:
Guide bearing shell (3) is a thrust bearing.
Observe bearing classification.
Installation note:
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).
Important!
Allocation of bearing points:
Bearing point 1 is at the front on the timing chain drive in the direction of travel.
Main bearing classification (1) for crankcase lower half (bedplate), code numbers 1 2 3, see table.
Observe bearing classification.
Bearing classification (2) of connecting rods code letters b and r.
Main bearing classification (1) in crankcase, code letters A / B or C, see table.
Installation note:
When all the letters and number code have been determined, the bearing shell colour must be allocated.
Installation note:
The letter / number combination produces a bearing shell pairing.
Identification by different colors.
Important!
First bearing point is on the timing drive.
The colour combination Yellow and Red must not be fitted.
Engine damage will result if excessively small bearing play is determined.
Code letters on crankcase:
Code letter A = bearing shell (1) colour Yellow.
Code letter B = bearing shell (1) colour Green.
Code letter C = bearing shell (1) colour Red.
Code numbers on crankshaft:
Code number 1 = bearing shell (2) Yellow.
Code number 2 = bearing shell (2) Green.
Code number 3 = bearing shell (2) Red.
Important!
The colour combination Yellow and Red must not be fitted; the bearing colors Green / Green must be selected for this colour combination, see table.
Installation example:
For bearing 1 with code letter A on the crankcase and code number 1 on the crankshaft bearing shell (1) with the colour
Yellow is required for the crankcase and bearing shell (2) with the colour Yellow for the crankcase lower half (bedplate).
Lager 2: A and 2 colors Yellow and Green.
Lager 3: B and 2 colors Green and Green.
Lager 4: C and 2 colors Red and Green.
Lager 5: B and 1 colors Green and Yellow.
Lager 6: C and 3 colors Red and Red.
Lager 7: C and 1 colors Green and Green.
The colour combination Yellow and Red must not be fitted.
Installation note:
Possible colour combinations for mounting the crankshaft in the crankcase.
Insert all bearing shells (2 and 3).
Important!
Clean sealing surfaces.
Do not clean sealing faces with a metal-cutting tool.
Only use special tool 11 4 470 to clean sealing surfaces.
Determine bearing play with special tool 00 2 590.
Installation note:
All measuring points must be free from oil and grease.
Use used screws to determine bearing play.
Set up crankcase lower section (bedplate) with bearing shells.
Remove crankcase lower section (bedplate).
Read off bearing play at width of flattened plastic thread and measurement scale.
Crankshaft bearing play radial.
Installation note:
Remove plastic thread.
Apply a light coat of oil to bearing shells and crankshaft.
Install crankcase lower section (bedplate).
Assemble engine.
e�f :
