11 24 571 Replacing all connecting rod bearing shells (N55)

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Special tools required:

IMPORTANT: Modified procedure:
All crank pins are connected with the crankshaft.
The Blue/Red connecting rod bearing shell colors are no longer fitted in combination.

Necessary preliminary work:

Remove oil sump. See REMOVING OIL SUMP (RWD) or REMOVING OIL SUMP (AWD) .

IMPORTANT: All crankshaft crank pins are classified.
The identification (2) is located on the first crank web.

Optional classifications (2) per connecting rod

On the connecting rod and connecting rod bearing cap:

Fig 1: Identifying Main Bearing ID Codes And Seat Assignment

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r. Connecting rod = Yellow.

Connecting rod bearing cap = Red.

b. Connecting rod = Violet.

Connecting rod bearing cap = Blue

Example:

Possible classification: b r r r r r

Zylinder1: Classification b

Violet (connecting rod)/\Blue (connecting rod bearing cap)

Zylinder2: Classification r

Yellow (connecting rod)/Red (connecting rod bearing cap)

Zylinder3: Classification r

Yellow (connecting rod)/Red (connecting rod bearing cap)

Zylinder4: Classification r

Yellow (connecting rod)/Red (connecting rod bearing cap)

Zylinder5: Classification r

Yellow (connecting rod)/Red (connecting rod bearing cap)

Zylinder6: Classification r

Yellow (connecting rod)/Red (connecting rod bearing cap)

Release connecting rod bolts (1).

Remove connecting rod bearing cap (2).

Fig 2: Identifying Connecting Rod Bearing Cap And Bolts

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WARNING: Risk of damage to cylinder wall and to crankshaft.

Gently release connecting rod from crankshaft.

Remove connecting rod bearing shells (1 and 2).

Fig 3: Identifying Connecting Rod Bearing Shells

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Use new connecting rod bearing shells according to code letter.

Installation note:

Pay attention to guide lugs during installation.

WARNING: All crankshaft crank pins are classified.

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

Check connecting-rod bearing play.

Piston in BDC position.

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

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

Fit connecting rod bearing cap so that pairing letters match up.

Fig 4: Locating Connecting Rod Bearing Cap Pairing Letters

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WARNING: Do not distort connecting rods or crankshaft.

Use the old connecting rod bolts to check connecting-rod bearing play.

Tighten down connecting rod bolts with special tool 00 9 120 .

Tightening torque 11 24 1AZ .

Fig 5: Tightening Connecting Rod Bolts Using Special Tool (00 9 120)

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Unscrew connecting rod bearing cap. Read off connecting-rod bearing play at width of flattened Plastigage on measuring scale.

CONNECTING-ROD BEARING PLAY .

Remove Plastigage
Coat crankshaft and connecting rod bearing shells with oil
Install new connecting rod bolts and tighten down with special tool 00 9 120 .

Tightening torque 11 24 1AZ .

Fig 6: Checking Flattened Plastigage Width Connecting Rod Bearing Play

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Assemble engine.