11 25 530 Removing and installing/replacing all pistons (N54, N54T)

WARNING: This page is about a different car, the 2013 BMW Z4, 2012 BMW Z4, 2011 BMW Z4, 2010 BMW Z4, and 2009 BMW Z4. However, it is still accessible from the selected car via links, so may be relevant.

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 by weight group.

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:

Remove ENGINE
Mount engine on ASSEMBLY STAND
Remove intake PLENUM
Remove CYLINDER HEAD
Remove OIL SUMP
Remove OIL PUMP

NOTE: In event of heavy oil carbon residue:

Carefully remove oil carbon residue from cylinder wall.

NOTE: Graphic shows N46.

Fig 1: Locating Oil Carbon Residue

Courtesy 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

Courtesy of BMW OF NORTH AMERICA, INC.

Release connecting rod bolts (1).

Tightening torque 11 24 1AZ .

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: Removing Connecting Rod Bearing Cap

Courtesy of BMW OF NORTH AMERICA, INC.

Screw special tool 11 8 590 into big end of connecting rod.

Press out connecting rod and piston to cylinder head side.

IMPORTANT: Risk of damage to oil spray nozzle.

Fig 4: Inserting Special Tool Into Big End Of Connecting Rod

Courtesy of BMW OF NORTH AMERICA, INC.

Preliminary work

Secure special tool 11 8 561 in vice.

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

Fig 5: Securing Piston Using Special Tool 11 8 561

Courtesy of BMW OF NORTH AMERICA, INC.

WARNING: Safety goggles must be worn for the next operation.

WARNING: Safety goggles must be worn.

To lever out piston circlip (1), support with 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 Using Special Tool 11 5 464

Courtesy of BMW OF NORTH AMERICA, INC.

Installation note:

If necessary, replace connecting rods.

IMPORTANT: Connecting rods are divided into weight classes and are only available as a set.

Old and new connecting rods must not be installed in mixed combinations.

Installation note:

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: Installing Gudgeon Pin

Courtesy 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

Courtesy 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 note:

If necessary, replace piston.

Fig 9: Checking Cylinder Bore Diameter

Courtesy of BMW OF NORTH AMERICA, INC.

WARNING: Safety goggles must be worn.

IMPORTANT: The opening of the piston pin circlip must be installed on the piston in the 6 o'clock position.

Risk of damage!

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

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

Fig 10: Inserting Piston Circlip Into Groove Of Special Tool 11 8 562

Courtesy of BMW OF NORTH AMERICA, INC.

WARNING: Safety goggles must be worn.

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

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

Fig 11: Identifying Special Tools 11 8 562 And 11 8 563

Courtesy of BMW OF NORTH AMERICA, INC.

WARNING: Safety goggles must be worn.

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

If the special tools 11 8 562 and 11 8 563 are not positioned correctly, the piston pin circlip must be driven in using a plastic hammer in direction of arrow.

NOTE: See graphic.

Fig 12: Inserting Piston Pin Circlip