11 25 530 Removing and installing/replacing all pistons (N52K)

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2010 BMW 528xi, 2010 BMW 528i, 2009 BMW 528xi, 2009 BMW 528i, and 2008 BMW 528xi. However, it is still accessible from the selected car via links, so may be relevant.

Special tools required:

WARNING: Danger of injury!
Carry out work on piston pin circlip wearing protective goggles only.

IMPORTANT: If piston, connecting rod, big end bearing cap and connecting rod bearing shell are to be reused, they must be installed in the same position.
Individual replacement of a connecting rod is not permitted. Connecting rods are classified by weight categories and are only available as a set for all cylinders.
Connecting rod and big end bearing cap are marked with identical pairing letters and must not be mixed up.
Danger of 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 oil sump
Remove OIL PUMP

NOTE: Carefully remove heavy oil carbon residues from the cylinder wall (arrow).

IMPORTANT: Do not use any metal-cutting tools.

Fig 1: Locating Heavy Oil Carbon

Courtesy of BMW OF NORTH AMERICA, INC.

IMPORTANT: Oil spray nozzle (2) must not be maladjusted or bent.
Risk of damage!

Do not release screw (1) of oil spray nozzle (2).

If necessary, readjust OIL SPRAY NOZZLE (2).

Fig 2: Identifying Screw And Oil Spray Nozzle

Courtesy of BMW OF NORTH AMERICA, INC.

Release conrod bolts (1).

Tightening torque 11 24 1AZ .

Installation:

Replace screws.

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

IMPORTANT: Connecting rod and big end bearing cap (2) are marked with identical pairing letters and must not be mixed up.
Danger of engine damage!

Fig 3: Identifying Conrod Bearing Cap And Bolts

Courtesy of BMW OF NORTH AMERICA, INC.

Attach special tool 11 8 330 to connecting rod.

Press out connecting rod and piston with special tool 11 8 330 to cylinder head side.

NOTE: Special tool 11 8 330 simultaneously serves to prevent connecting rod and piston from falling down.

IMPORTANT: Do not touch the oil spray nozzle when removing the components.
Risk of damage!

Fig 4: Identifying Special Tool 11 8 330

Courtesy of BMW OF NORTH AMERICA, INC.

Preliminary work:

Clamp special tool 11 4 491 in vice.

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

Fig 5: Securing Piston With Connecting Rod To Special Tool

Courtesy of BMW OF NORTH AMERICA, INC.

WARNING: Danger of injury!
Carry out work on piston pin circlip wearing protective goggles only.

WARNING: Protective goggles must be worn.

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

Fig 6: Removing Piston Pin Circlip With Special Tool 11 4 492

Courtesy of BMW OF NORTH AMERICA, INC.

If necessary, replace connecting rods.

IMPORTANT: Individual replacement of a connecting rod is not permitted. Connecting rods are classified by weight categories and are only available as a set for all cylinders.
Existing and new connecting rods must not be installed in mixed combinations.

Installation:

It must be possible for the piston pin to be pressed with minimal force by hand through the small end bushing. There must be no noticeable play.

Fig 7: Pressing Piston Pin

Courtesy of BMW OF NORTH AMERICA, INC.

Measure piston installation clearance:

Measure piston diameter with micrometer at measuring point "A" from lower edge of piston and offset by 90° to piston pin axis.

PISTON DIAMETER at measuring point "A".

Fig 8: Measuring Piston Diameter With Micrometer

Courtesy of BMW OF NORTH AMERICA, INC.

Adjust micrometer to cylinder bore of crankcase. 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. See ENGINE, GENERAL , ENGINE BLOCK and PISTON WITH RINGS .

If necessary, replace piston.

Fig 9: Measuring Cylinder Bore

Courtesy of BMW OF NORTH AMERICA, INC.

WARNING: Protective goggles must be worn.

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

Move piston pin circlip (2) into installation position.

Fig 10: Inserting Piston Pin Circlip Into Groove Of Special Tool

Courtesy of BMW OF NORTH AMERICA, INC.

WARNING: Protective goggles must be worn.

Guide lug and cutout on special tool 11 4 493 must point to piston crown. Only then can special tool 11 4 494 be correctly fitted.

When special tools 11 4 493 and 11 4 494 are correctly positioned, the piston pin circlip must be driven in with a plastic hammer in the direction of the arrow.

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

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: For vehicles with B30 engines.

Install all PISTON RINGS .

Install all CONNECTING ROD BEARING SHELLS .

Coat piston (2) and piston rings with oil.

Pre-install piston (2) in special tool 11 6 261 .

Attach special tool 11 8 330 to connecting rod (1).

Installation:

Check protective lugs on special tool 11 8 330 for correct position and damage.

Fig 12: Identifying Piston And Connecting Rod

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: For vehicles with B25 engines.

Install all PISTON RINGS .

Install all CONNECTING ROD BEARING SHELLS .

Coat piston (2) and piston rings with oil.

Pre-install piston (2) in special tool 11 6 241 .

Attach special tool 11 8 330 to connecting rod (1).

Installation:

Check protective lugs on special tool 11 8 330 for correct position and damage.

Fig 13: Attaching Special Tool 11 8 330 To Connecting Rod

Courtesy of BMW OF NORTH AMERICA, INC.

Insert piston (1) with connecting rod in cylinder.

IMPORTANT: Do not touch the oil spray nozzle when installing the components.
Risk of damage!
Danger of piston ring failure.

Press in piston (1) at marked points (see arrows) with finger pressure only, do not drive in.

Insert piston (1) so that arrow (2) on piston crown points to camshaft drive.

Press in piston (1) with special tools 116 261 /11 6 241 .

Fig 14: Identifying Piston And Arrow Mark

Courtesy of BMW OF NORTH AMERICA, INC.

IMPORTANT: Connecting rod and big end bearing cap are marked with identical pairing letters (1) and must not be mixed up.
Mixing them up or incorrectly fitting the big end bearing cap on the connecting rod will result in engine damage.

Fig 15: Identifying Marked With Identical Pairing Letters

Courtesy of BMW OF NORTH AMERICA, INC.

Apply a light coat of oil to connecting rod bearing journal. Join connecting rod and connecting rod bearing journal.

Detach special tool 11 8 330 .

Fig 16: Identifying Special Tool 11 8 330

Courtesy of BMW OF NORTH AMERICA, INC.

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

Installation:

Replace screws.

Install new conrod bolts (1).

IMPORTANT: Jointing torque and angle of rotation must be observed without fail.
Risk of damage!

Tightening torque 11 24 1AZ .

Fig 17: Identifying Conrod Bearing Caps And Conrod Bolts

Courtesy of BMW OF NORTH AMERICA, INC.

If necessary, tighten connecting rod bolts to torsion angle with special tool 00 9 120 .

Tightening torque 11 24 1AZ .

Fig 18: Identifying Special Tool 00 9 120

Courtesy of BMW OF NORTH AMERICA, INC.

Assemble engine.