11 25 671 Replacing piston rings on all pistons (N54, N54T)

WARNING: This page is about a different car, the 2013 BMW Z4, 2012 BMW Z4, 2011 BMW Z4, 2010 BMW Z4, and 2009 BMW Z4. However, it is still accessible from the selected car via links, so may be relevant.

Necessary preliminary tasks:

Remove all PISTONS .

Measuring axial clearance of piston rings in piston ring groove.

TECHNICAL DATA.

NOTE: It is not possible to measure the axial clearance of the oil scraper rings.

Fig 1: Checking Piston Ring Clearance

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Remove compression ring and stepped ring upwards with piston ring pliers.

Oil scraper ring comprises two steel band rings and a support spring.

NOTE: Oil scraper ring cannot be removed with piston ring pliers.

Put aside piston rings in correct sequence and installation position.

It might not be possible to find the identification on used piston rings.

Installation note:

New pistons may only be installed together with new piston rings.

Fig 2: Removing Compression Ring And Stepped Ring

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Determine See ENGINE BLOCK, CYLINDER CRANKCASE N54/B30 or PISTONS WITH RINGS AND PINS N54/B30 with a feeler gauge.

Fig 3: Determining Piston Ring Gap Using Filler Gauge

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NOTE: Schematic diagram of piston rings.

Installation note:

Piston rings with "TOP" identification must point to piston crown.

Plain compression ring
Piston ring "top"
Two-part oil scraper ring

Fig 4: Identifying Piston Rings

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NOTE: Oil control ring comprises two steel band rings (1) and a support spring (2).

Installation note:

Insert support spring (2) into piston ring groove and then fit steel band rings (1) so that contact points are offset by approx. 120°.

Fig 5: Identifying Steel Band Ring And Support Spring

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Offset the contact points (1) of the piston rings by approx. 120° to each other but do not position above the gudgeon pin boss.

NOTE: See graphic N52.

Fig 6: Identifying Piston Rings Contact Point

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Assemble engine.