Connecting Rod Bearing: Service and Repair

11 24 571 - Replacing all connecting rod bearing shells (N52K)





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





Important!
All crank pins are connected with the crankshaft.

Modified procedure: The colours of the connecting rod bearing shells are the same at the top and bottom.

The Blue / Red connecting rod bearing shell colours are no longer fitted in combination.





Necessary preliminary tasks:
- Remove oil sump Service and Repair





Important!
All crankshaft crank pins are classified.

Possible classifications per connecting rod at top and bottom:

r: - Red
b: - Blue
Only one colour may be fitted per big end bearing cap and connecting rod.

In direction of arrow from (1 to 2) crank pin (1 to 6).

Example:
Possible classification: rbbrrb

Cylinder 1: - Classification Red / Red
Cylinder 2: - Classification Blue / Blue
Cylinder 3: - Classification Blue / Blue
Cylinder 4: - Classification Red / Red
Cylinder 5: - Classification Red / Red
Cylinder 6: - Classification Blue / Blue





Release conrod bolts (1).

Remove connecting rod bearing cap (2).





Important!
Risk of damage to cylinder wall and to crankshaft.

Gently release connecting rod from crankshaft.

Remove connecting rod bearing shells (1 and 2).

Install new conrod bearing shells.

Installation Note:
Pay attention to guide lugs during installation.

Important!
All crankshaft crank pins are classified.

In each case insert only one colour of connecting rod bearing shell (1 and 2) for each connecting rod.





Check conrod bearing clearance.

Piston in BDC position.

To determine the connecting rod bearing play, make sure that the bearing points are clean and free from oil and grease.

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

Fit conrod bearing cap so that pairing letters match up.





Important!
Do not distort conrods or crankshaft.

Use the old conrod bolts to check conrod clearance.

Tighten down conrod bolts with special tool 00 9 120.

Tightening torque 11 24 1AZ. Mechanical Specifications





Unscrew conrod bearing cover. Read off conrod bearing play at width of flattened plastic thread on measurement scale.

Conrod bearing clearance.

- Remove Plastigage
- Coat crankshaft and connecting rod bearing shells with oil
- Install new conrod bolts and tighten down with special tool 00 9 120.
Tightening torque 11 24 1AZ. Mechanical Specifications





Assemble engine.