11 25 530 Removing and installing/replacing all pistons (N52)

WARNING: This page does not describe the selected car, but rather 16 other vehicles, including the 2008 BMW Z4, 2007 BMW Z4, 2007 BMW 530xi, 2007 BMW 530i, and 2007 BMW 525xi. However, it is still accessible from the selected car via links, so may be relevant.

Special tools required:

00 9 120
11 4 491
11 4 492
11 4 493
11 6 241
11 6 261
11 8 330
11 9 493
11 9 494

WARNING: Protective goggles must be worn when working on the piston pin circlip.

IMPORTANT: If pistons, conrods and bearing shells are reused, they must be reinstalled in the same places.

Individual conrod replacement is not permitted; they are classified according to weight categories.

Conrods and conrod bearing caps are denoted with the same pairing letters; mixing them up will result in engine damage.

Piston and piston pins are paired and must not be fitted individually.

Necessary preliminary tasks:

Remove Engine.
Mount engine on Assembly Stand.
Remove Intake Air Manifold.
Remove Cylinder Head.
Remove Engine Oil Sump.
Remove Oil Pump.

NOTE: In event of heavy oil carbon residue:

Carefully remove oil carbon residue from cylinder wall.

NOTE: Illustrations show N46.

Fig 1: Identifying Engine Cylinder Wall

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 Oil Spray Nozzle And Mounting Screw

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Release conrod bolts (1).

For tightening torque refer to 11 24 1AZ in 11 24 CONNECTING RODS AND BEARINGS (N52) .

Remove conrod bearing cap (2) in direction of arrow.

IMPORTANT: Conrods and conrod bearing caps are denoted with the same pairing letters; mixing them up will result in engine damage.

Fig 3: Identifying Connecting Rod Bearing Cap And Bolts

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Attach special tool 11 8 330 in conrod big end.

Press out conrod and piston to cylinder head side.

IMPORTANT: Risk of damage to oil spray nozzle.

Fig 4: Identifying Special Tool (11 8 330)

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Preliminary work:

Clamp special tool 11 4 491 in a vice.

Secure piston (1) with conrod to special tool 11 4 491.

Fig 5: Identifying Special Tool (11 4 491) And Piston

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WARNING: Protective goggles must be worn for the next work step.

WARNING: Protective goggles must be worn.

Lever out piston circlip with special tool 11 4 492 in direction of arrow.

Fig 6: Identifying Special Tool (11 4 492)

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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 piston 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 Piston Pin In Connecting Rod

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Measure 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 piston pin.

Piston diameter at measuring point A.

Fig 8: Measuring Piston Clearance

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Adjust micrometer to cylinder bore of engine block. Set internal caliper 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.

If necessary, replace piston.

Fig 9: Measuring Diameter Of Cylinder Bore Of Engine Block

Courtesy of BMW OF NORTH AMERICA, INC.

WARNING: Protective goggles must be worn.

Insert piston circlip (2) into groove (1) of special tool 11 4 493.

Bring piston circlip into assembly position.

Fig 10: Identifying Special Tool (11 4 493), Piston Circlip And Groove

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WARNING: Protective goggles must be worn.

Guide lug and cutout on special tool 11 9 493 must point to the piston crown; only then can special tool 11 9 494 be correctly fitted.

When special tools 11 9 493 and 11 9 494 are correctly positioned, the piston pin circlip must be driven in with a plastic hammer in the direction of the arrow.

NOTE: See Fig 11.

Fig 11: Identifying Special Tool (11 4 493) And (11 4 494)