11 25 530 Removing and installing/replacing all pistons (N14)

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

Special tools required:

00 9 120
11 9 620
11 9 670

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

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

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

Piston and gudgeon 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: Cylinder Wall

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NOTE: Mark all pistons and conrods with a pen prior to removing.

Example:

Direction of arrow (1) points to camshaft drive.

Cylinder allocation (2) per cylinder.

Fig 2: Arrow Direction And Cylinder Allocation

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NOTE: Mark all pistons and conrods with a pen prior to removing.

Example:

Mark cylinder allocation (1) per cylinder.

Direction of arrow (2) points to camshaft drive.

Fig 3: Cylinder Allocation Mark And Arrow Direction

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Release connecting rod bolts (1).

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

Remove conrod bearing cap.

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

Fig 4: Connecting Rod Bolts

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IMPORTANT: Risk of damage! to oil spray nozzle.

Attach special tool 11 9 620 in conrod big end.

Press out connecting rod and piston to cylinder head side.

Fig 5: Special Tool (11 9 620)

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

WARNING: Protective goggles must be worn.

IMPORTANT: Piston and gudgeon pins are paired and must not be fitted individually.

Lever out piston pin circlip with a screwdriver in direction of arrow.

Fig 6: Piston Pin Circlip And Removal Direction

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If necessary, replace connecting rods.

Installation:

The gudgeon pin must be able to be pressed through the liner by hand with little force and must not display any significant play.

Fig 7: Gudgeon Pin And Installation Direction

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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 gudgeon pin.

Piston diameter at measuring point A.

Fig 8: Measuring Piston Diameter

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Adjust micrometer to cylinder bore of engine block. Set internal calliper on micrometer to zero. Measure bottom, centre 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

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Install all Piston Rings .

Install all Bearing Shells .

Coat piston and piston rings with oil .

Pre-install piston in special tool 11 9 670 .

Screw special tool 11 9 620 into conrod.

Installation:

Check protective lugs on special tool 11 9 620 for correct position and damage.

Fig 10: Special Tools (11 9 620) And (11 9 670)

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Insert piston with connecting rod in cylinder.

IMPORTANT: Danger of piston ring failure.

Press in piston with finger pressure only, do not drive in (see arrows in Fig 11).

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

If reusing the pistons, assign cylinder allocation (2) to correct cylinder.

Press in piston with special tool 11 9 670 .

Fig 11: Cylinder Allocation, Piston, Special Tool (11 9 670) And Installation Direction

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IMPORTANT: Point of fracture (1) on conrod.

Conrod and conrod bearing cap are identified with pairing letters (2) and must not be mixed up.

Mixing them up or incorrectly fitting the conrod bearing cap on the big end will result in engine damage .

Both pairing letters (2) must be together on one side.

Fig 12: Pairing Letters And Point Of Fracture

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Apply a light coat of oil to crank pin.

Assemble connecting rod and crank pin.

Remove special tool 11 9 620 .

Fig 13: Special Tool (11 9 620)

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

Check cylinder identification markings (1).

Direction of arrow (2) points to camshaft drive.

Fig 14: Cylinder Allocation Markings And Bearing Caps

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Install new connecting rod bolts (1).

Carry out torsion angle tightening of conrods with special tool 00 9 120 .

For tightening torque refer to 11 24 1AZ in 11 24 CONNECTING RODS AND BEARINGS

Fig 15: Connecting Rod Bolts

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Assemble engine.