11 25 530 Removing and installing or replacing all pistons (M52 / S52 / M52TU / M54 / M56): 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. Refer to 11 41 000 REMOVING AND INSTALLING/REPLACING OIL PUMP (M52TU / M54 / M56) .

If oil pump and oil scraper are two parts: Remove oil scraper.

Fig 1: Removing Oil Scraper

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NOTE: Figure shows crankshaft removed.

Fig 2: View Of Spray Nozzle For Piston Cooling

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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.

In event of heavy oil carbon residue:

Carefully remove oil carbon residue from cylinder wall.

Fig 3: Removing Oil Carbon Residue From Cylinder Wall

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Unscrew connecting rod bearing cover.

Fig 4: Unscrewing Connecting Rod Bearing Cover

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Insert special tool 11 3 480 in connecting rod.

Fig 5: Removing Connecting Rod With Piston From Cylinder Head Side

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Remove connecting rod with piston from cylinder head side.

Lift out retaining ring and press out piston pin.

Fig 6: Lifting Out Retaining Ring And Pressing Out Piston Pin

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