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11 25 530 Removing and installing/replacing all pistons (N54)

WARNING: This page is about a different car, the 2010 BMW X6, 2009 BMW X6, and 2008 BMW X6. However, it is still accessible from the selected car via links, so may be relevant.

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 piston pin circlip.
IMPORTANT: If pistons, connecting rods and bearing shells are reused, they must be reinstalled in the same places.
Individual connecting rod replacement is not permitted; they are classified according to weight categories.
Connecting rods and connecting rod bearing caps are marked with the same pairing letters; mixing them up will result in engine damage.
Piston and gudgeon pins are paired and must not be fitted individually.

Necessary preliminary tasks: 

NOTE: In event of heavy oil carbon residue:

Carefully remove oil carbon residue from cylinder wall.

NOTE: Illustrations show N46.
Fig 1: Locating Oil Carbon Residue
G04751123Courtesy of BMW OF NORTH AMERICA, INC.

Do not  release screw (1).

Oil spray nozzle  (2) must not be maladjusted or bent.

If necessary, readjust (risk of damage). 

Fig 2: Identifying Screw And Oil Spray Nozzle
G04751124Courtesy of BMW OF NORTH AMERICA, INC.

Release connecting rod bolts (1).

Tightening torque 11 24 1AZ  , see 11 24 CONNECTING RODS AND BEARINGS

Remove connecting rod bearing cap (2) in direction of arrow.

IMPORTANT: Connecting rods and connecting rod bearing caps are marked with the same pairing letters; mixing them up will result in engine damage.
Fig 3: Identifying Connecting Rod Bolts And Connecting Rod Bearing Cap
G04751125Courtesy of BMW OF NORTH AMERICA, INC.

Screw special tool 11 8 590  into base of connecting rod.

Press out connecting rod and piston to cylinder head side.

IMPORTANT: Risk of damage  to oil spray nozzle.
Fig 4: Identifying Special Tool 11 8 590
G04754892Courtesy of BMW OF NORTH AMERICA, INC.

Preliminary work: 

Clamp special tool 11 8 561  in a vice.

Secure piston (1) with connecting rod to special tool 11 8 561  .

Fig 5: Identifying Piston And Special Tool 11 8 561
G04754893Courtesy of BMW OF NORTH AMERICA, INC.
WARNING: Protective goggles  must be worn for the next work step.
WARNING: Protective goggles  must be worn.

To lever out piston circlip (1), support special tool 11 5 464  on piston (2).

Lever out piston circlip (1) with special tool 11 5 464  in direction of arrow.

Fig 6: Removing Piston Circlip
G04754894Courtesy of BMW OF NORTH AMERICA, INC.

Installation: 

If necessary, replace connecting rods. 

IMPORTANT: Connecting rods are divided into weight categories and are only available as a set.
Old and new connecting rods must not be installed in mixed combinations.

Installation: 

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 7: Identifying Gudgeon Pin And Connecting Rod
G04751129Courtesy of BMW OF NORTH AMERICA, INC.

Measuring piston installation clearance: 

Measure piston diameter with micrometer at measuring point A from bottom edge of piston and offset at 90° to the axis of the gudgeon pin.

Piston diameter at measuring point A.

Fig 8: Measuring Piston Diameter With Micrometer At Measuring Point A From Bottom Edge Of Piston
G04739771Courtesy of BMW OF NORTH AMERICA, INC.

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.

Diameter of cylinder bore.

Piston installation clearance.

Total permissible wear tolerance  .

Installation: 

If necessary, replace piston. 

Fig 9: Measuring Bottom, Centre And Top Of Cylinder Bore In Direction Of Travel And Direction Of Engine Rotation
G04739772Courtesy of BMW OF NORTH AMERICA, INC.
WARNING: Protective goggles  must be worn.
IMPORTANT: The opening of the piston pin circlip must be installed in the 6 o'clock position  on the piston.
Risk of damage! 

Insert piston circlip (2) into groove of special tool 11 8 562  .

Bring piston circlip (2) into assembly position (1).

Fig 10: Bring Piston Circlip Into Assembly Position
G04754898Courtesy of BMW OF NORTH AMERICA, INC.
WARNING: Protective goggles  must be worn.

Slide special tool 11 8 563  up to piston pin circlip (2)

Special tools 11 8 562  and 11 8 563  are prepared.

Fig 11: Sliding Special Tool 11 8 563 Up To Piston Pin Circlip
G04754899Courtesy of BMW OF NORTH AMERICA, INC.
WARNING: Protective goggles  must be worn.

Cutout on special tool 11 8 562  must point to piston crown; only then can special tool 11 8 563  be correctly fitted.

When special tools 11 8 562  and 11 8 563  are correctly positioned, the piston pin circlip must be driven in with a plastic hammer in the direction of the arrow.

Fig 12: Installing Piston Pin Circlip
G04754900Courtesy of BMW OF NORTH AMERICA, INC.

Piston pin circlip is correctly installed when opening (1) points downwards.

Fig 13: Identifying Piston Pin Circlip Opening Points
G05501675Courtesy of BMW OF NORTH AMERICA, INC.
NOTE: B 30.
Install all piston rings   .
Install all bearing shells  .
Coat piston and piston rings with oil.
Pre-install piston (2) in special tool 11 8 141  .
Screw on special tool 11 8 590  in connecting rod (2).

Installation: 

Check protective lugs (1) on special tool 11 8 590  for correct position and damage.

Fig 14: Identifying Special Tools (11 8 141, 11 8 590)
G04754902Courtesy of BMW OF NORTH AMERICA, INC.

Insert piston with connecting rod in cylinder.

IMPORTANT: Risk of damage to oil spray nozzle.
Danger of piston ring failure.
Press in piston in direction of arrow with finger pressure only, do not drive in.

Insert piston so that arrow on piston crown points to camshaft drive.

Press in piston (1) with special tool 11 8 141  .

Fig 15: Identifying Special Tool 11 8 141
G04754903Courtesy of BMW OF NORTH AMERICA, INC.
IMPORTANT: Connecting rod and connecting rod bearing cap are marked with pairing letters (1) and must not be mixed up.
Mixing them up or incorrectly fitting the connecting rod bearing cap on the big end will result in engine damage. 
Fig 16: Identifying Connecting Rod And Connecting Rod Bearing Cap Mark
G04751137Courtesy of BMW OF NORTH AMERICA, INC.

Apply a light coat of oil to crank pin.

Assemble connecting rod and crank pin.

Screw off special tool 11 8 560  in counterclockwise direction.

Fig 17: Identifying Special Tool 11 8 560
G04754892Courtesy of BMW OF NORTH AMERICA, INC.

Fit bearing caps (2) so that pairing letters match up.

Install new connecting rod bolts (1).

Tightening torque 11 24 1AZ  , see 11 24 CONNECTING RODS AND BEARINGS

Fig 18: Identifying Bearing Caps And Connecting Rod Bolts
G04751118Courtesy of BMW OF NORTH AMERICA, INC.

Adjust torsion angle of conrod with special tool 00 9 120 

Tightening torque 11 24 1AZ  , see 11 24 CONNECTING RODS AND BEARINGS

Fig 19: Adjusting Torsion Angle Of Conrod With Special Tool 00 9 120
G04751121Courtesy of BMW OF NORTH AMERICA, INC.

Assemble engine.

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