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 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 groove in piston before checking clearance.

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 pistons approx. 10 mm from the lower edge of skirt, at 90° to the piston pin axis. Difference between actual and nominal diameter: 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 -A-and longitudinal -B- directions, as illustrated. Difference between actual and nominal diameter: 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.