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

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Special tools required: 

See MAINTENANCE AND GENERAL INFORMATION - SPECIAL TOOLS .

See ENGINE - SPECIAL TOOLS (N54, N63) .

WARNING: Protective goggles must be worn when working on the gudgeon pin circlip.
IMPORTANT: If pistons and connecting rods are reused, they must be reinstalled in the same places.

Piston and piston pin are matched to each other and can only be replaced as a pair.

Conrod and conrod 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.

Conrod bearings must always be replaced.

Necessary preliminary tasks: 

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

Fig 1: Releasing Connecting Rod Bolts
G00530105Courtesy of BMW OF NORTH AMERICA, INC.

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

Fig 2: Screwing Special Tool Into Connecting Rod
G00530106Courtesy of BMW OF NORTH AMERICA, INC.
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 special tool 2 249 164 towards the cylinder head side.

Fig 3: Positioning Crankshaft Central Bolt
G06178497Courtesy of BMW OF NORTH AMERICA, INC.
IMPORTANT: Pistons and gudgeon pins are paired and must not be fitted individually.

Lift out circlip and press out piston pin.

Fig 4: Pressing Retaining Ring
G04773660Courtesy of BMW OF NORTH AMERICA, INC.

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: Pressing Piston Pin
G04739770Courtesy of BMW OF NORTH AMERICA, INC.

Prior to installation, measure piston installation clearance: Measure piston diameter with micrometre at measuring point A from lower edge of piston and offset at 90° to the axis of the gudgeon pin. See PISTON WITH RINGS AND PIN .

Fig 6: Checking Piston Diameter With Micrometer
G04739771Courtesy of BMW OF NORTH AMERICA, INC.

Adjust micrometre to cylinder bore of engine block. Set internal measuring device on micrometre to zero. Measure bottom, center and top of cylinder bore in direction of travel and direction of rotation. See ENGINE BLOCK and PISTON WITH RINGS AND PIN .

Fig 7: Checking Cylinder Bore Diameter
G04739772Courtesy of BMW OF NORTH AMERICA, INC.

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

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

Fig 8: Installing Piston Circlip
G04741627Courtesy of BMW OF NORTH AMERICA, INC.

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

Fig 9: Installing Conrod Bearing
G06178506Courtesy of BMW OF NORTH AMERICA, INC.

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.

Fig 10: Identifying Piston Ring Contact Point Offset Position
G04741640Courtesy of BMW OF NORTH AMERICA, INC.

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: Identifying Special Tool (11 7 280)
G06178508Courtesy of BMW OF NORTH AMERICA, INC.

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

Fig 12: Identifying Piston Mark
G06178510Courtesy of BMW OF NORTH AMERICA, INC.

Connect the crankshaft journal and connecting rod. Remove the special tools 2 249 164.

Fig 13: Attaching Crankshaft Journal To Connecting Rod
G06888576Courtesy of BMW OF NORTH AMERICA, INC.
NOTE: For purposes of clarity, the pairing letters (1) are shown on the removed connecting rod.
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 14: Identifying Pairing Letters
G04739781Courtesy of BMW OF NORTH AMERICA, INC.

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 15: Identifying Conrod Bearing Caps
G04739767Courtesy of BMW OF NORTH AMERICA, INC.

Secure connecting rod bolts (1) with special tool 00 9 120. Tightening torque 11 24 1 AZ.

Fig 16: Tightening Connecting-Rod Bearing Cap Bolt
G06178493Courtesy of BMW OF NORTH AMERICA, INC.
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