Removing and installing or replacing all pistons (S63T2) (X5 M)

Special tools required: 

• 00 9 120
• 11 5 440
• 11 7 280
• 11 8 151
• 11 8 152
• 2 249 164

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 .
• MOUNT ENGINE ON ASSEMBLY STAND. 
• Remove RIGHT CYLINDER HEAD  or LEFT CYLINDER HEAD .
• Remove OIL SUMP .
• Remove OIL PUMP .

To release the connecting rod bolts (1), the crankshaft (2) must be moved to a suitable position.

Release connecting rod bolts (1).

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Screw the special tool 2 249 164 into the connecting rod.

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Position crankshaft at central bolt.

Press out the connecting rod and piston with the special tool 2 249 164 towards the cylinder head side.

Attention! 

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

Lift out snap ring and press out piston pin.

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If necessary, replace connecting rods.

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). Refer to RINGS AND BOLTS TECHNICAL DATA .

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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. Refer to PISTON WITH RINGS AND BOLTS TECHNICAL DATA .

Total permissible WEAR CLEARANCE .

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See illustration.

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

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Insert the special tools 2 249 164 into the 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.

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

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Connect the crankshaft journal and connecting rod.

Remove the special tools 2 249 164.

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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 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.