Check the end clearance of the new piston rings

Prerequisite

Cylinder barrel is cleaned. Cylinder was measured and is within the permissible tolerances.

NOTE: Schematic diagram is for example purposes. Some parts may differ in certain details.

Place new piston rings (1) into the cylinder to be measured and turn through 90° in direction of the arrow.

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Position all new piston rings (1) in succession in the cylinder barrel below the top dead center (arrow).

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Press in all new piston rings in succession with the help of the piston (1) up to the last annular groove (arrows) in parallel.

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Check

In succession, measure the end clearance of all piston rings as shown with a feeler gauge.
Determining the correct set of the piston ring (see applicable BMW parts catalogue):

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Engine	Set of the piston rings	Pistons	End clearance piston rings, top (plain rectangular compression ring)	End clearance piston rings, middle (taper faced piston ring)
B38M1 ECE	8 693 017	8 678 931	0.2 - 0.3 mm	0.4 - 0.6 mm
B38M1 ECE	8 693 017	9 494 399	0.2 - 0.3 mm	0.4 - 0.6 mm
B48M1 ECE	8 693 017	8 678 931	0.2 - 0.3 mm	0.4 - 0.6 mm
B48M1 ECE	8 693 017	9 494 399	0.2 - 0.3 mm	0.4 - 0.6 mm
B38M1 CN	8 693 017	8 678 931	0.2 - 0.3 mm	0.4 - 0.6 mm
B38M1 CN	9 847 276	8 681 079	0.2 - 0.3 mm	0.4 - 0.6 mm
B48M1 CN	8 693 017	8 678 931	0.2 - 0.3 mm	0.4 - 0.6 mm
B48M1 CN	9 847 276	8 681 079	0.2 - 0.3 mm	0.2 - 0.3 mm
B48O1 ECE+CN	8 693 017	8 678 934	0.2 - 0.3 mm	0.4 - 0.6 mm
B48T1 ECE+CN	9 846 014	9 488 343	0.2 - 0.3 mm	0.2 - 0.3 mm
B58M1	9 847 276	8 681 079	0.2 - 0.3 mm	0.2 - 0.3 mm
B58O1	9 693 017	8 678 934	0.2 - 0.3 mm	0.4 - 0.6 mm

Desired State

Result

» The end clearance of the piston rings is outside of the tolerance.

Measure