11 25 671 Replacing Piston Rings On All Pistons (N12)

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:

11 9 670

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: Identifying Piston Rings Groove 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:

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

Fig 2: Removing Piston Ring

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Determine gap with a feeler gauge.

Fig 3: Identifying Piston Ring Gap With Feeler Gauge

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Installation:

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

Fig 4: Identifying Piston Rings With "TOP" Identification Point

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Installation:

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

Plain compression ring
Taper face ring
Two-part oil scraper ring

IMPORTANT: Contact point on oil scraper ring (3) can overlap - risk of damage! - during installation in cylinder.

Fig 5: Identifying Compression Ring, Taper Face Ring And Two-Part Oil Scraper Ring

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NOTE: The oil control ring comprises a steel band ring (1) and a support spring (2).

Installation:

Insert support spring (2) in piston ring groove and then fit steel band ring (1) so that end faces point to each other.

Fig 6: Identifying Support Spring And Steel Band Ring

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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 piston pin boss. Coat special tool 11 9 670 with sufficient engine oil. Risk of damage to piston rings!

Fig 7: Identifying Contact Points Of Piston Rings

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Assemble engine.