Volkswagen Workshop Service and Repair Manuals

Checking piston and cylinder bore

Checking piston ring gap Special tools and workshop equipment required t  Feeler gauges –  Push ring squarely from above down into cylinder bore to approx. 15 mm from bottom end of cylinder.

Piston ring		Ring gap
		New	Wear limit
Compression rings	mm	0.20 … 0.40	0.8
Oil scraper ring	mm	0.25 … 0.50	0.8

Checking ring-to-groove clearance Special tools and workshop equipment required t  Feeler gauges –  Clean annular groove before check.

Piston ring		Clearance
		New	Wear limit
Compression rings	mm	0.06 … 0.09	0.20
Oil scraper ring	mm	0.03 … 0.06	0.15

Checking piston Special tools and workshop equipment required t  Micrometer 75 - 100 mm -VAS 6071- –  Measure approx. 10 mm from lower edge of skirt, at 90° to piston pin axis. Deviation from nominal dimension max. 0.04 mm

Checking cylinder bores Special tools and workshop equipment required t  Cylinder gauge -VAS 6078- –  Take measurements at 3 positions in both lateral direction -A- and longitudinal direction -B-. –  Deviation from nominal dimension max. 0.08 mm   Note Cylinder bores must not be measured when cylinder block is mounted on a repair stand with engine and gearbox support -VAS 6095-, as measurements may then be incorrect. Piston and cylinder dimensions   Caution The cylinder bore may not be worked on (reboring, honing, grinding) may not be carried out using workshop tools! This will damage the surface of the cylinder bore.

		Piston Ø	Cylinder bore Ø
Basic dimension	mm	82.4651)	82.51

1) Dimensions without graphite coating (thickness 0.02 mm). The graphite coating wears away.