11 25 530 Removing and installing or replacing all pistons (M57T2-SCR)

Necessary preliminary work:

Remove ENGINE .
Remove CYLINDER HEAD .
Removing OIL SUMP .
Remove OIL PUMP .

IMPORTANT: Re-install the piston, connecting rod and bearing shells back in the same location and in the same installation position .
Connecting rods and bearing caps are designated with the same matching number: do not mix them .
Replace connecting rod bolts .

Unscrew connecting rod bearing cap.

Pull out connecting rod and piston to the cylinder head side.

IMPORTANT: Position crankshaft vertically.
Proceed with care at the cylinder wall and oil spray nozzles Risk of damage.

Fig 1: Locating Connecting Rod Bearing Cap

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Preliminary work

Secure special tool 116111, 116110, 116112, 116113 in vice.

Secure piston (1) with connecting rod to special tool 11 6 111.

Graphic shows N52.

Fig 2: Securing Special Tool (11 6 111) On Vice

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WARNING: Safety goggles must be worn for the next operation.

WARNING: Safety goggles must be worn.

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

IMPORTANT: Piston and gudgeon pin are matched to each other.
They must not be mixed up.

Fig 3: Removing Piston Circlip Using Special Tool (11 4 492)

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Before installation, measure piston installation clearance. Measure piston diameter with micrometre at measuring point A from lower edge of piston and offset at 90° to the axis of the gudgeon pin. Distance A, Refer to TECHNICAL DATA

Fig 4: Measuring Piston Diameter Using Micrometre

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Adjust micrometre to cylinder bore of engine block. Set internal measuring device on micrometre to zero. Measure bottom, center and top of cylinder bore in direction of travel and direction of rotation.

Diameter of the cylinder bore,

Refer to TECHNICAL DATA

Piston installation clearance,

Refer to TECHNICAL DATA

Permitted total wear clearance,

Refer to TECHNICAL DATA

Fig 5: Measuring Diameter Of Cylinder Bore

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If necessary, replace connecting rods.

The BMW Parts Department only supplies connecting rods in complete sets.

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

Fig 6: Pressing Gudgeon Pin

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Replace CONNECTING ROD BEARING SHELLS .

Fit connecting rod to piston in such a way that both of the visible matching numbers on the arrow indicating direction of installation on the piston point to the right.

Fig 7: Locating Piston Installing Matching Numbers

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WARNING: Safety goggles must be worn.

Insert piston circlip (2) into groove (1) of special tool 11 6 112.

Bring piston circlip into installation position.

Fig 8: Inserting Piston Circlip Into Groove Of Special Tool (11 6 112)

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WARNING: Safety goggles must be worn.

Guide lug and aperture on special tool 11 6 112 must point to piston crown; only then can special tool 11 6 113 be fitted correctly.

If special tools 11 6 112 and 11 6 113 are correctly positioned, the piston the circlip for gudgeon pin must be driven in with a plastic hammer in the direction of the arrow.

NOTE: See graphic.

Fig 9: Inserting Gudgeon Pin

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Insert special tool 11 6 330 in connecting rod.

Lightly coat pistons and piston rings with oil.

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

Fig 10: Inserting Special Tool (11 6 330) On Connecting Rod

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Press together piston rings with special tool 11 8 140.

Install piston so that arrow points to camshaft drive.

IMPORTANT: Risk of piston ring breakage.

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

Fig 11: Pressing Piston Rings Using Special Tool (11 8 140)

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Attach crankshaft journal to connecting rod.

Remove special tool 11 6 330.

Fig 12: Identifying Special Tool (11 6 330)

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Apply light coat of oil to connecting rod bearing shells.

Fit bearing caps so that matching numbers match up.

Installation note:

Use new connecting rod bolts.

Fig 13: Locating Bearing Caps Matching Numbers

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Tighten down connecting rod bolts with special tool 00 9 120.

Installation note:

Tightening torque, see 11 24 1AZ in CONNECTING RODS AND BEARINGS .

Fig 14: Tightening Connecting Rod Bolt Using Special Tool (00 9 120)

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The gasket thickness must be recalculated when repair work is carried out on the crankshaft drive or pistons.

Measuring the piston protrusion:

Fit dial gauge with measuring fixture special tool 00 2 530 on cleaned engine block sealing surface and set to zero under preload.

Fig 15: Measuring Piston Protrusion

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Position piston at TDC.

Clean piston at measuring points (1 and 2).

Fit dial gauge at measuring point (1) on piston and determine highest point by rotating crankshaft.

Measure and note down piston protrusion at measuring points (1 and 2) on all pistons.

Fig 16: Measuring Highest Piston Protrusion

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The highest piston protrusion at the measuring points (1 and 2) of all the pistons determines the thickness of the cylinder head gasket.

Piston protrusion 0.92... 1.03 mm

Install 2-hole cylinder head gasket.

Piston protrusion over 1.03 mm

Install 3-hole cylinder head gasket.

Thickness of cylinder head gasket (1).

Fig 17: Identifying Cylinder Head Gasket

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Assemble engine.

Check engine function and check for leak tightness.