A6 Quattro Sedan V6-2.7L Turbo (APB) (2000)
Piston: Service and Repair
Pistons and piston rings, checking
Pistons
Position: arrow on piston crown must always face in direction of travel.
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Mark cylinder number on piston crown with waterproof felt pen.
Note: Do not use a center-punch or similar, as pistons have a special coating.
Checking piston diameter
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Measure pistons approximately 10 mm from bottom of skirt, at 90° to piston pin axis.
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Difference between actual and nominal diameter: not more than 0.04 mm.