Necessary preliminary tasks

Remove ENGINE
Install engine on assembly stand
Remove LEFT CYLINDER HEAD .
Remove RIGHT CYLINDER HEAD .
Removing oil pan. See LOWER OIL SUMP SECTION and UPPER OIL SUMP SECTION
Remove OIL PUMP

Unscrew connecting rod bearing cap.

NOTE: Connecting rods and connecting rod bearing caps are denoted with the same pairing letters.
The stamped dates are always arranged in opposite directions.
Set down conrod bearing caps in order.

Fig 1: Locating Connecting Rod Bearing Caps Stamped Dates

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NOTE: To install and remove the conrods, it is essential for the crankshaft to be exactly in alignment with the cylinder bore (see dashed line).

Position crankshaft at central bolt.

Insert special tool 11 8 152 into conrod.

Screw special tool 11 5 440 into conrod with bolt (1).

Remove conrod with piston from cylinder head side.

Fig 2: Removing Conrod With Piston From Cylinder Head Side

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IMPORTANT: Piston and piston bolts are paired and must not be fitted individually.

Lift out retaining ring and press out piston pin.

Fig 3: Removing Retaining Ring From Piston

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If necessary, replace connecting rods.

NOTE: The conrods can also be replaced individually.
The gudgeon pin must be able to be pressed through the liner by hand with little force and must not display any significant play.

Fig 4: Installing Gudgeon Pin

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Prior to installation, measure piston installation clearance: Measure piston diameter with micrometer at measuring point A from lower edge of piston and offset by 90° to piston pin axis.

Refer to MEASURING POINT A .

Fig 5: Measuring Piston Diameter

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Adjust micrometer to cylinder bore of engine block. Set internal calliper on micrometer to zero. Measure bottom, center and top of cylinder bore in direction of travel and direction of engine rotation.

Refer to:

Fig 6: Checking Diameter Of Cylinder Bore

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IMPORTANT: The conrods of cylinder banks 1 to 4 and 5 to 8 are mounted to the pistons differently.

NOTE: The pistons and conrods of cylinders 1 to 8 are identical.

Arrow on piston crown (cyl. 1 to 4) points upwards, bolt connection on conrod points at an angle to right.

Fig 7: Identifying Arrow On Piston Crown

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Arrow on piston crown (cyl. 5 to 8) points upwards, bolt connection on conrod points at an angle to left.

NOTE: For purposes of clarity, pistons are shown removed.

The conrods are correctly mounted on the piston when the bolt connections on the conrods are parallel to each other (see arrow).

Fig 8: Identifying Bolt Connections On Conrods Are Parallel To Each Other

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Install retaining ring.

Fig 9: Installing Retaining Ring

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Installation:

Piston circlip (1) is correctly installed when the opening points upwards.

See illustration.

It must still be possible for the piston pin to moved easily.

Fig 10: Locating Piston Circlip

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Insert special tools 11 8 151 and 11 8 152 into conrod.

INSTALL CONNECTING ROD BEARING .

Fig 11: Inserting Special Tools 11 8 151 And 11 8 152 Into Conrod

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Lightly coat pistons and piston rings with oil.

Offset the contact points of the piston rings by approx. 120° to each other but do not position above the piston pin boss.

NOTE: Illustration shows S85.

Fig 12: Identifying Piston Rings Offset Contact Points

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Keep piston rods compressed with special tool 11 7 280 .

Install piston so that arrow points to camshaft drive.

IMPORTANT: Danger of piston ring failure.

Press in piston only with finger force (do not knock in!).

Fig 13: Compressing Piston Rods With Special Tool 11 7 280

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IMPORTANT: Danger of piston ring failure.

Press in piston (1) only with finger force (do not knock in!).

Fig 14: Pressing In Piston Only With Finger Force

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The direction arrow on the piston crown must point to the camshaft drive (direction of travel towards front).

Fig 15: Identifying Arrow Direction On Piston Crown Must Point To Camshaft Drive (Direction Of Travel Towards Front)

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Attach crankshaft journal to connecting rod.

Remove special tools 11 5 440 and 11 8 152.

Fig 16: Attaching Crankshaft Journal To Connecting Rod

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NOTE: For purposes of clarity, the pairing letters (1) are shown on the removed conrod.

IMPORTANT: Conrods and conrod bearing caps are denoted with the same pairing letters (1), do not mix them up.
Fit bearing cap so that pairing letters match up.

Fig 17: Identifying Conrods And Conrod Bearing Caps Pairing Letters

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Apply light coat of oil to connecting-rod bearing shells.

Fit bearing cap so that pairing letters match up.

Install new conrod bolts.

Fig 18: Locating Conrod Bolts

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Tighten down connecting rod bolts (1) with special tool 00 9 120 .

Tightening torque 11 24 1 AZ .

Fig 19: Tightening Down Connecting Rod Bolts With Special Tool 00 9 120

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Assemble engine.