Crankshaft Main Bearing: Service and Repair

11 21 531 Replacing all crankshaft main bearings (N18)

Special tools required:





Important!
Modified assignment of bearing positions.
Bearing position (1) is at the output end (clutch end)
Determine main bearing colors; the designations on the crankcase and crankshaft are always required and can only determined using the table.
Because of the central bolt on the timing chain drive, bearing seat 5 requires a different bearing classification.





Necessary preliminary work:
^ Remove crankshaft.





Installation note:
Bearing shell (1) with lubricating groove must be fitted on crankcase upper part.

Bearing shell (2) without lubricating groove must be fitted on crankcase lower section (bedplate).





Important!
Modified assignment of bearing positions.
Bearing position (1) is at the output end (clutch end)

Bearings (1 to 5).

Bearing (2) is a guide bearing.

Important!
Clean sealing surfaces.
Do not clean sealing surfaces with a metal-cutting tool.

Only use special tool 11 4 470 to clean sealing surfaces.





Insert guide rings (1) in crankcase at bearing seat (2) with groove facing outwards.

If necessary, attach with engine oil to crankcase.





Bearing classification on crankcase upper and lower section:
Bearing allocation 1 - 5: the designations on the crankshaft are always required.

Refer to the table for the colour code.

Example:
Lager 1. Letter P

Lager 2. Letter K

Lager 3. Letter I

Lager 4. Letter N

Lager 5. Letter N

Bearing classification on crankcase upper and lower section:
Bearing allocation 1 - 5: the designations on the crankcase are always required.

Refer to the table for the colour code.

Example:
Lager 1. Letter T

Lager 2. Letter Q





Lager 3. Letter Q

Lager 4. Letter R

Lager 5. Letter R

Example: Crankshaft / crankcase.

Bearing (1):

The letter P of the shaft and letter T on the crankcase result in the bearing colors for assignment to the crankcase Or= Orange with lubricating groove.

Letter P of the shaft and letter T on the crankcase result in the bearing colors for assignment to the crankcase - lower section (bedplate) Ge = Yellow without lubricating groove.

Bearing (2):

The letter K of the shaft and letter Q on the crankcase result in the bearing colors for assignment to the crankcase Or= Orange with lubricating groove.

Letter K of the shaft and letter Q on the crankcase result in the bearing colors for assignment to the crankcase - lower section (bedplate) Or = Orange without lubricating groove.

Bearing (3):

The letter I of the shaft and letter Q on the crankcase result in the bearing colors for assignment to the crankcase Or= Orange with lubricating groove.

Letter I of the shaft and letter Q on the crankcase result in the bearing colors for assignment to the crankcase - lower section (bedplate) Or = Orange without lubricating groove.

Bearing (4):

The letter N of the shaft and letter R on the crankcase result in the bearing colors for assignment to the crankcase Ge= Yellow without lubricating groove.

Letter N of the shaft and letter R on the crankcase result in the bearing colors for assignment to the crankcase - lower section (bedplate) Ge = Yellow without lubricating groove.

Attention! Note additional table.

Bearing (5):

The letter N of the shaft and letter R on the crankcase result in the bearing colors for assignment to the crankcase Ge= Yellow with lubricating groove.

Letter N of the shaft and letter R on the crankcase result in the bearing colors for assignment to the crankcase - lower section (bedplate) Gr = Green without lubricating groove.





Crankshaft bearing colors bearing position 1-4

Sw = Black.

Gr = Green.

Ge = Yellow.

Or = Orange.

Br = Brown.











Crankshaft bearing colors bearing position 5:

Sw = Black.

Gr = Green.

Ge = Yellow.

Or = Orange.

Br = Brown (in the upper part of the crankcase only).











Install crankcase lower section.

Assemble engine.