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Home >> BMW >> 2004 >> 525i Standard >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine - Repair (M54) >> Piston With Rings And Pin >> 11 25 530 Removing and installing or replacing all pistons (M52 / S52 / M52TU / M54 / M56) >> Removal & Installation

Removal & Installation

(engine removed)

Remove Cylinder Head .

Removal: 

Removal of pistons is described separately from installation.

Assembly sequence for removal and installation is different.

IMPORTANT: Re-install piston, connecting rod and bearing shells back in the same position and in the same installation location.

Connecting rods and bearing covers are designated with the same pair number: do not mix them.

Remove Oil Pump .

If oil pump and oil scraper are two parts:

Remove oil scraper.

Fig 1: Removing Oil Scraper
G03260559Courtesy of BMW OF NORTH AMERICA, INC.
NOTE: Figure shows crankshaft removed.

On engines with spray nozzles for piston cooling on cylinder underside:

IMPORTANT: When removing and installing pistons, make sure the piston cooling spray nozzles are not damaged.

Installation: 

Screw threads are coated with screw securing adhesive (Loctite). Replace screws.

Fig 2: Identifying Spray Nozzles For Piston Cooling On Cylinder Underside
G03260560Courtesy of BMW OF NORTH AMERICA, INC.

In event of heavy oil carbon residue:

Carefully remove oil carbon residue from cylinder wall.

Fig 3: Removing Oil Carbon Residue From Cylinder Wall
G03260561Courtesy of BMW OF NORTH AMERICA, INC.

Unscrew conrod bearing cover.

Fig 4: Unscrewing Conrod Bearing Cover
G03260562Courtesy of BMW OF NORTH AMERICA, INC.

Insert special tool 11 3 480 in conrod.

Remove conrod with piston from cylinder head side.

Fig 5: Inserting Special Tool In Conrod
G03260563Courtesy of BMW OF NORTH AMERICA, INC.

Lift out retaining ring and press out piston pin.

IMPORTANT: Piston and piston pin are paired and must not be fitted individually.
Fig 6: Lifting Out Retaining Ring And Pressing Out Piston Pin
G03260564Courtesy of BMW OF NORTH AMERICA, INC.

Installation: 

Installation of pistons is described separately from removal. The assembly sequence differs between removal and 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: Installing Piston Pin
G03260565Courtesy of BMW OF NORTH AMERICA, INC.

Measure piston installation clearance:

Measure piston diameter with micrometer at distance A from the underside of the piston and at offset angle of 90° to piston pin axis.

Fig 8: Measuring Piston Installation Clearance
G03260566Courtesy of BMW OF NORTH AMERICA, INC.

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.

Fig 9: Measuring Cylinder Bore
G03260567Courtesy of BMW OF NORTH AMERICA, INC.

Replace Conrod Bearing Shells .

IMPORTANT: Piston and piston pin are paired and must not be fitted individually.

Fit conrod with piston pin to piston in such a way that both of the visible pair numbers on the installation direction arrow on the piston point to the right.

Fig 10: Replacing Conrod Bearing Shells
G03260568Courtesy of BMW OF NORTH AMERICA, INC.

Install snap ring so that opening is opposite recess.

Fig 11: Installing Snap Ring
G03260569Courtesy of BMW OF NORTH AMERICA, INC.

Insert special tool 11 2 470 in conrod.

Fig 12: Inserting Special Tool In Conrod
G03260570Courtesy of BMW OF NORTH AMERICA, INC.

Lightly coat pistons and piston rings with oil.

Align contact points on piston rings (offset at approx. 120°, but do not arrange over piston pin lug).

NOTE: Piston diameter 84 mm: Use special tool 11 8 141. Piston diameter 80 mm: Press together piston rings with special tool 11 2 260.
Fig 13: Pressing Together Piston Rings With Special Tool
G03260571Courtesy of BMW OF NORTH AMERICA, INC.

Install piston so that arrow points to camshaft drive.

Entire circumference of tightening strap must rest firmly on engine block.

IMPORTANT: Danger of piston ring failure.

Press in piston only with finger force (do not knock in!).

Fig 14: Installing Piston
G03260572Courtesy of BMW OF NORTH AMERICA, INC.

Attach crankpin to connecting rod.

Fig 15: Attaching Crankpin To Connecting Rod
G03260573Courtesy of BMW OF NORTH AMERICA, INC.

Apply light coat of oil to connecting-rod bearing shells.

Fit bearing caps so that pair numbers match up.

Install new conrod bolts.

Fig 16: Fitting Bearing Caps
G03260574Courtesy of BMW OF NORTH AMERICA, INC.

Tighten down conrod bolts with special tool 00 9 120 or special tool 11 2 110.

Tightening torque, see 11 24 1AZ in ENGINE - TIGHTENING TORQUES .

Fig 17: Tightening Down Conrod Bolts With Special Tool
G03260575Courtesy of BMW OF NORTH AMERICA, INC.

Install Oil Pump .

If oil pump and oil scraper are two parts:

Fit oil scraper.

Assemble engine.

Fig 18: Fitting Oil Scraper
G03260576Courtesy of BMW OF NORTH AMERICA, INC.
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