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

WARNING: This page is about a different variant/trim than selected.

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 Axial Clearance

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.

Fig 2: Checking Piston Ring Clearance Using Piston Ring Pliers

Installation note:

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

Determine gap See TED-TED-TDMUC1111-N54-01B1S1 ENGINE BLOCK, CYLINDER CRANKCASE, BMW, N54, B30 or TED-TED-TDMUC1125-N54-02B1S1 PISTONS WITH RINGS AND PINS N54/B30 with a feeler gauge.

Fig 3: Checking Piston Ring Gap Using Feeler Gauge

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 Plain Compression Ring, Piston Ring Top And Two Part Oil Scraper Ring

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

Fig 5: Identifying Steel Band Ring And Support Ring

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°.

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 Ring Contact Point Offset

Assemble engine.