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 Test procedure –  Push ring squarely from above down into cylinder bore 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 gauges Test procedure Clean ring groove before checking.

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 Test procedure Measure pistons approx. 10 mm from lower edge of skirt, at 90° to piston pin axis. Deviation from nominal dimension max. 0.04 mm

Bearing shells - installation position Bearing shell -1- with oil hole -arrow- for conrod. Bearing shell -2- without oil hole for conrod bearing cap. –  Fit bearing shells in centre of conrod and conrod cap. Dimension -a- must be the same on the left and right.

Checking cylinder bores Special tools and workshop equipment required t  Internal dial test indicator 50...100 mm –  Take measurements at 3 points both across -A- and in-line -B- with engine. 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 -VW 540-, as measurements may then be incorrect.