Volkswagen Workshop Service and Repair Manuals

Piston rings, cylinder bore and piston installation position

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

Piston ring dimensions in mm	New	Wear limit
1st compression ring	0.20...0.40	1.0
2nd compression ring	0.20...0.40	1.0
Oil scraper ring	0.25...0.50	1.0

Checking ring-to-groove clearance Special tools and workshop equipment required t  Feeler gauges –  Clean groove in piston before checking clearance.

Piston ring dimensions in mm	New	Wear limit
1. compression ring	0.06...0.09	0.25
2. compression ring	0.05...0.08	0.25
Oil scraper ring	0.03...0.06	0.15

Checking cylinder bore Special tools and workshop equipment required t  Internal dial gauge 50...100 mm –  Take measurements at 3 positions in both transverse -A- and longitudinal -B- directions, as illustrated. Difference between actual and nominal diameter: not more than 0.10 mm.   Note Cylinder bores must not be measured when cylinder block is mounted on a repair stand with engine support bracket -VW 540-, as measurements may then be incorrect.

Piston installation position and allocation of piston to cylinder. Piston in cylinders 1 and 2: Larger inlet valve chamber -arrows- towards flywheel. Piston in cylinders 3 and 4: Larger inlet valve chamber towards belt pulley side -arrows-.   Note t  New piston allocation to cylinders is shown by a coloured marking on piston crown. t  Piston for cylinders 1 and 2: marked 1/2 t  Piston for cylinders 3 and 4: marked 3/4