Volkswagen Workshop Service and Repair Manuals

Checking pistons, piston rings and cylinder bores

Checking piston ring gap Special tools and workshop equipment required t  Feeler gauge (commercially available). –  Push ring squarely from above down to approx. 15 mm from bottom end of cylinder.

Piston 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 gauge (commercially available). Clean groove before check.

Piston ring		Ring-to-groove 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  External micrometer 75...100 mm Measure pistons approx. 10 mm from the lower edge of skirt, at 90° to the piston pin axis. Deviation from nominal dimension max. 0.04 mm.

Checking cylinder bores Special tools and workshop equipment required t  Internal dial test indicator 50..100 mm   Note Cylinder bores must not be measured when cylinder block is mounted on support clamp -VW 313- with engine and gearbox support -VW 540-, as measurements may then be incorrect. –  Take measurements at 3 positions in both lateral -A- and longitudinal -B- directions, as illustrated. Deviation from nominal dimension max. 0.08 mm.