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11 25 530 Removing And Installing/Replacing All Pistons (N62)

WARNING: This page is about a different car, the 2008 BMW Alpina and 2007 BMW Alpina. However, it is still accessible from the selected car via links, so may be relevant.

Special tools required: 

(engine removed)

Removal 

Removal of pistons is described separately from installation. Assembly sequence for removal and installation is different.

Mount engine on assembly stand. 

Remove both cylinder heads.

Unscrew oil sump.

Remove oil pump.

CAUTION: Re-install piston, connecting rod and bearing shells back in the same position and in the same installation location.
Conrods and conrod bearing caps are denoted with the same pairing letters, do not mix them up.

In event of heavy oil carbon residue:

Carefully remove oil carbon residue from cylinder wall.

Fig 1: Locating Cylinder Wall
G04739765Courtesy of BMW OF NORTH AMERICA, INC.
CAUTION: When removing and installing pistons, make sure piston cooling spray nozzles (1) are not damaged.
Fig 2: Identifying Piston Cooling Spray Nozzles
G04739766Courtesy of BMW OF NORTH AMERICA, INC.

Remove connecting-rod cover.

NOTE: Conrods and conrod bearing caps are denoted with the same pairing letters.
Set down conrod bearing caps in order.
Fig 3: Identifying Bearing Cap Bolts
G04739767Courtesy of BMW OF NORTH AMERICA, INC.

Insert special tools 11 8 151  and 11 8 152  in conrod.

Remove connecting rod with piston from cylinder-head side.

Fig 4: Identifying Special Tool
G04773670Courtesy of BMW OF NORTH AMERICA, INC.
CAUTION: Piston and piston bolts are paired and must not be fitted individually.

Lift out retaining ring and press out piston pin.

Fig 5: Lifting Out Retaining Ring
G04773660Courtesy of BMW OF NORTH AMERICA, INC.

Installation 

Installation of pistons is described separately from removal. The assembly sequence for removal and installation is different.

If necessary, replace connecting rods.

NOTE: The conrods can also be replaced individually.
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 6: Pressing Piston Pin
G04739770Courtesy of BMW OF NORTH AMERICA, INC.

Prior to installation, 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.

Measuring point A.  For specifications, refer to ENGINE - TECHNICAL DATA .

Fig 7: Measuring Piston Diameter
G04776965Courtesy 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.  For specifications, refer to ENGINE - TECHNICAL DATA .

Total permissible wear tolerance.  For specifications, refer to ENGINE - TECHNICAL DATA .

Fig 8: Measuring Cylinder Bore
G04739772Courtesy of BMW OF NORTH AMERICA, INC.
NOTE: The pistons and conrods of cylinders 1 to 8 are identical.
CAUTION: The conrods of cylinder banks 1 to 4 and 5 to 8 are mounted to the pistons differently.

Cylinder bank 1 to 4 

Fit conrod with piston pin to piston in such a way that arrow on piston points to front and flat end of conrod points to rear.

Fig 9: Identifying Dowel Sleeves
G04776967Courtesy of BMW OF NORTH AMERICA, INC.

Cylinder bank 5 to 8 

Fit conrod with piston pin to piston in such a way that arrow on piston points to front and flat end of conrod points to rear.

Install conrod bearing.  See 11 24 571 REPLACING ALL CONROD BEARINGS (N62/N62TU) .

Fig 10: Installing Piston Pin
G04773666Courtesy of BMW OF NORTH AMERICA, INC.

Install retaining ring.

Fig 11: Installing Retaining Ring
G04739775Courtesy of BMW OF NORTH AMERICA, INC.

Insert special tools Z11 8 151  and 11 8 152  in conrod.

Fig 12: Identifying Special Tool
G04776970Courtesy of BMW OF NORTH AMERICA, INC.

N62 B44 

Lightly coat pistons and piston rings with oil.

Offset the contact points of the piston rings by approx. 120° to each other but do not position above the piston pin boss.

Compress piston rings with special tool 11 9 500. 

Fig 13: Identifying Special Tool (11 9 500)
G04776971Courtesy of BMW OF NORTH AMERICA, INC.

N62 B44 

Keep piston rings compressed with special tool 11 9 500. 

Install piston so that arrow points to camshaft drive.

CAUTION: Danger of piston ring failure.

Only press pistons into place with finger force - do not knock in!

Fig 14: Identifying Special Tool (11 9 500)
G04776972Courtesy of BMW OF NORTH AMERICA, INC.

N62 B36 

Lightly coat pistons and piston rings with oil. Offset the contact points of the piston rings by approx. 120° to each other but do not position above the piston pin boss.

Slide special tool 11 8 141  over piston (1).

Install piston so that arrow points to camshaft drive.

Fig 15: Identifying Special Tool (11 8 141)
G04776973Courtesy of BMW OF NORTH AMERICA, INC.
CAUTION: Danger of piston ring failure.

Only press pistons into place with finger force - do not knock in!

Attach crankpin to connecting rod.

Remove special tools 11 8 151  and 11 8 152. 

Fig 16: Identifying Special Tool
G04773670Courtesy of BMW OF NORTH AMERICA, INC.
NOTE: For purposes of clarity, the pairing letters (1) are shown on the removed conrod.
CAUTION: Conrods and conrod bearing caps are denoted with the same pairing letters (1), do not mix them up.
Fig 17: Identifying Conrod Bearing Caps Pairing Letters
G04739781Courtesy of BMW OF NORTH AMERICA, INC.

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

Fit bearing cap so that pairing letters match up.

Install new connecting-rod screws.

Fig 18: Identifying Bearing Cap Bolts
G04739767Courtesy of BMW OF NORTH AMERICA, INC.

Secure conrod with special tool 00 9 120. 

Tightening torque. See ENGINE - TIGHTENING TORQUES -- ALPINA .

Fig 19: Identifying Special Tool (00 9 120)
G04739762Courtesy of BMW OF NORTH AMERICA, INC.
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