Replacing All Main Crankshaft Bearing Shells
11 21 531 - Replacing all main crankshaft bearing shells (N63)
Special tools required:
- 00 2 590
- 00 9 120
- 11 6 251
- 11 6 252
Important!
Risk of injury from sharp crankcase edges.
Necessary preliminary tasks:
- Remove crankshaft Service and Repair
Note:
Main bearing caps 1 to 5 are marked with punched numbers.
Observe crankshaft construction stage:
S: - Series
B: - Repair stage 1
C: - Repair stage 2
The letters denote the bearing shell classification for the relevant bearing position from 1 to 5 (main bearing cap).
The first letter on the left applies to the first bearing position at the front on the timing chain drive.
color coding on crankshaft 1 to 5
Y= yellow
G= green
V= violet
The letters 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 on the timing chain drive.
color coding in crankcase 1 to 5.
Y= yellow
G= green
V= violet
Installation Note:
Install main bearing shells (1) with lubrication groove in crankcase.
Install main bearing shells (2) without lubrication groove in the main bearing caps.
Note:
Main bearing cap number 3 can be identified by the surfaces (1) for the stop discs of the thrust bearing.
Turn back thread support bushing into main bearing cap.
Checking main bearing clearance:
To check crankshaft bearing clearance, use the existing main bearing screws.
Important!
Danger of cracking!
No oil is permitted in the blind bores.
Do not twist crankshaft.
Place special tool 00 2 590 (Plastigage model PG 1) on oil-free crankshaft (see arrow).
Tighten down all collar bolts (M11) of main bearing caps in sequence 1 to 5 to jointing torque.
Tightening torque 11 11 1AZ 11 11 Engine Block.
Tighten down all collar bolts (M11) of main bearing caps with special tool 00 9 120 to angle of rotation.
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
- Apply a coat of oil to new bearing shells and crankshaft
Note:
Always replace bolts in main bearing caps with new bolts.
Do not wash off bolt coating.
Important!
Danger of cracking!
No oil is permitted in the blind bores.
Install crankshaft Service and Repair.
Carefully strike back and front of crankshaft with a plastic hammer to center thrust bearing (do not damage crankshaft).
Secure special tool 11 6 252 with magnetic foot on crankcase.
Position special tool 11 6 251 .
Tightening specifications for main bearing:
Check axial play 11 21 Crankshaft and Bearings.
Check guide bearing shell, crankshaft and crankcase if necessary.
Assemble engine.