Removing and installing/replacing all pistons (S63) (X6 M)

Special tools required:

00 9 120
11 5 440
11 7 280
11 8 151
11 8 152

WARNING: Safety goggles must be worn when working on the gudgeon pin snap ring.

Attention!

If pistons and connecting rods are reused, they must be reinstalled in the same places.

Pistons and gudgeon pins are matched to each other and can only be replaced as a pair.

Connecting rod and connecting rod bearing cap are cracked.

Identification is effected by means of identical pairing letters on the connecting rod big end.

Mixing up the components will result in engine damage.

Connecting rod bearings must always be replaced.

Necessary preliminary work:

Remove ENGINE .
MOUNTING ENGINE ON ASSEMBLY STAND .
Remove RIGHT CYLINDER HEAD and LEFT CYLINDER HEAD .
Remove OIL SUMP .
Remove OIL PUMP .

Attention!

Mixed installation of the connecting rod with different tightening specifications

Loosen screws.

Unscrew connecting rod bearing cap.

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

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NOTE: For installation and dismantling of the connecting rods, 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 connecting rod.

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

Remove connecting rod with piston from cylinder head side.

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Attention!

Pistons and gudgeon pins are paired and must not be fitted individually.

Lift out circlip and press out piston pin.

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If necessary, replace connecting rods.

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

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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 at 90° to the axis of the gudgeon pin.

Measuring point A.

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

Diameter of cylinder bore.

Piston installation clearance.

Total permissible wear clearance.

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Attention!

The connecting rods of cylinder banks 1 to 4 and 5 to 8 are fitted to the pistons differently.

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

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

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Arrow on piston crown (cyl. 5 to 8) points upwards, screw connection on connecting rod points at an angle to left.

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

The connecting rods are correctly mounted on the piston when the screw connections on the connecting rods are parallel to each other (see arrow).

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Install snap ring.

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Installation note:

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

See graphic.

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

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Insert special tools 11 8 151 and 11 8 152 into connecting rod.

Install connecting rod bearing.

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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 gudgeon pin boss.

NOTE: Picture shows S85.

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Keep piston rings compressed with special tool 11 7 280.

Install piston so that arrow points to camshaft drive.

Attention!

Risk of breakage of piston rings.

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

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Attention!

Risk of breakage of piston rings.

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

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

NOTE: Graphic shows N63.

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Attach crankshaft journal to connecting rod.

Remove special tools 11 5 440 and 11 8 152.

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

Attention!

Connecting rods and connecting rod bearing caps are denoted with the same pairing letters (1), do not mix them up.

Fit bearing cap so that pairing letters match up.

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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 connecting rod bolts.

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Different tightening torque values for the installed connecting rods!

Differentiating connecting rods:

Curved connecting rod
Straight connecting rod

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

Tightening torque 11 24 1 AZ. .

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Apply light coat of oil to connecting rod bearing shells.

Fit the bearing cap so that the pairing letters (3) match up.

Install the connecting rod bolts (1).

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

Tightening torque 11 24 1AZ .

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Assemble engine.