11 25 530 Removing and installing/replacing all pistons (N63 hybrid car) from 3/2011

WARNING: This page is about a different car, the 2011 BMW X6 and 2010 BMW X6. However, it is still accessible from the selected car via links, so may be relevant.

Special tools required:

WARNING: Safety goggles must be worn when performing repair work on the piston pin circlip.

IMPORTANT: 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 tasks:

Remove ENGINE
Mount engine on assembly stand.
Remove both cylinder heads. See LEFT CYLINDER HEAD and RIGHT CYLINDER HEAD .
Remove oil sump. See UPPER OIL SUMP SECTION and LOWER OIL SUMP SECTION .
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).

Fig 1: Identifying Crankshaft And Connecting Rod Bolts

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

Fig 2: Installing Special Tool (2 249 164) Into Connecting Rod

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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.

Position crankshaft at central bolt.

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

Fig 3: Removing Connecting Rod And Piston Using Special Tool (2 249 164)

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

Lift out circlip and press out piston pin.

Fig 4: Pressing 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.

Fig 5: Locating 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 at 90° to the axis of the gudgeon pin.

MEASURING POINT A .

Fig 6: Measuring Piston Diameter Using Micrometer

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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: see ENGINE BLOCK, CYLINDER CRANKCASE and ENGINE IN GENERAL .

See PISTON INSTALLATION CLEARANCE .

See TOTAL PERMISSIBLE WEAR CLEARANCE .

Fig 7: Measuring Bottom, Centre And Top Of Cylinder Bore Using Micrometer

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Installation note:

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

See Fig 8.

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

Fig 8: Identifying Piston Circlip

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Insert the special tools 2 249 164 into the connecting rod.

Install conrod bearing.

Fig 9: Inserting Special Tools (2 249 164) Into Connecting Rod

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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: Graphic S85.

Fig 10: Identifying Piston Top Surface

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Keep piston rings compressed with special tool 11 7 280 .

Install piston so that arrow points to camshaft drive.

IMPORTANT: Risk of breakage of piston rings.

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

Fig 11: Pressing Piston With Finger Force

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Keep piston rings compressed with special tool 11 7 280 .

Install piston so that arrow points to camshaft drive.

IMPORTANT: Risk of breakage of piston rings.

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

Fig 12: Installing Piston Using Finger Force And Special Tool (11 7 280)

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

Fig 13: Identifying Direction Arrow On Piston Crown

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Connect the crankshaft journal and connecting rod.

Remove the special tools 2 249 164 .

Fig 14: Connecting Crankshaft Journal And Connecting Rod

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IMPORTANT: 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.

Fig 15: Identifying Pairing Letters On Connecting Rods And Bearing Caps

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NOTE: For purposes of clarity, the pairing letters (1) are shown on the removed connecting rod.
Graphic shows connecting rod before 3/2011.

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).

Fig 16: Locating Connecting Rod Mounting Bolts

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

Tightening torque 11 24 2 AZ .

Graphic shows front connecting rod screw connection 3/2011.

Fig 17: Tightening Connecting Rod Bolts Using Special Tool (00 9 120)

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Assemble engine.