11 25 530 Removing and installing/replacing all pistons (S54): Installation

WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.

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

The piston pin must be able to be pressed through the liner by hand with little force and must not display any significant play. If necessary, replace connecting rods.

Fig 1: Installing Piston Pin

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NOTE: Only conrods of the same weight group are allowed to be installed inside an engine. The BMW Parts Service only supplies connecting rods in complete sets.

Prior to installation, 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 piston pin. For measuring point A, refer to 11 25 PISTONS WITH RINGS AND PINS S54 .

Fig 2: Locating Measuring Point

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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.

Fig 3: Measuring Cylinder Bore

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Diameter of cylinder bore, refer to 11 00 ENGINE IN GENERAL S54 .
Piston installation clearance, refer to 11 25 PISTONS WITH RINGS AND PINS S54 .
Permitted total wear clearance, refer to 11 25 PISTONS WITH RINGS AND PINS S54 .

CAUTION: Piston and piston pins 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 4: Fitting Conrod

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Install retaining ring.

Fig 5: Installing Retaining Ring

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CAUTION: Note grinding stages on crankshaft. Refer to 11 21 CRANKSHAFT AND BEARINGS S54 .

NOTE: Classified conrod bearing shells color-coded "Yellow and Green" are installed in the model series. The classification is removed when the conrod bearing shells are replaced.

Install conrod bearing shells (1) color-coded "Blue" in conrod at top
Install conrod bearing shells (2) color-coded "Red" in conrod at top

Fig 6: Installing Conrod Bearing Shells

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For M10x1.25, insert special tool 11 2 050 in conrod.

Fig 7: Inserting Special Tool

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For M11x1.25, insert special tool 11 3 480 in conrod.

Fig 8: Inserting Special Tool

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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 9 120.

Fig 9: Compressing Piston Rings

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Keep piston rings pressed with special tool 11 9 120. Install piston so that arrow points to camshaft drive.

Fig 10: Installing Piston

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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 tool 11 2 050 or 11 3 480.

CAUTION: Conrod with M10x1.25 conrod bolt: Conrod bolts (B) are made from a material which only reaches its maximum tensile strength after they have been tightened three times. Connecting rod bolts (B) must be tightened at least three times but no more than five times. The tightening specifications detailed in the following must be observed exactly. Mixing up the procedure for replacing the conrods and conrod bolts and the tightening specifications will result in serious engine damage.

Check connecting rod bearing clearance: Piston in BDC position. Fit special tool 00 2 590 (Plastigage Type PG 1) to the oil-free crankshaft.

Fig 11: Checking Connection Rod Bearing Clearance

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Fit bearing caps so that pair numbers match up.

Fig 12: Fitting Bearing Caps

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