Piston And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2018 Audi Q3 Quattro, 2018 Audi Q3, 2017 Audi Q3 Quattro, and 2017 Audi Q3. However, it is still accessible from the selected car via links, so may be relevant.

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-- Measure approximately 15 mm from the lower edge at a 90° angle to the piston pin axis using a 75 to 100 mm external micrometer.

Deviation from specified size: maximum 0.04 mm

		Piston Diameter
Standard dimension	mm	82.42 ¹⁾
¹⁾ Measurement without coating (thickness = 0.02 mm). The coating wears off.

Fig 1: Piston Ring Gap, Checking

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-- Push the piston ring squarely from above down to approximately 15 mm from the edge of the cylinder. To push in use a piston without rings.

Piston Ring Dimensions in mm	New	Wear Limit
1. Compression ring	0.30 to 0.40 mm	0.80 mm
2. Compression ring	0.40 to 0.50 mm	0.80 mm
Two-piece oil scraping ring	0.20 to 0.40 mm	0.80 mm
Three-piece oil scraping ring	Cannot be measured

Fig 2: Piston Ring Groove Clearance

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-- Clean the piston ring groove before checking.

Piston Ring Dimensions in mm	New	Wear Limit
1. Compression ring	0.06 to 0.09 mm	0.20 mm
2. Compression ring	0.03 to 0.06 mm	0.15 mm
Oil scraping rings	Cannot be measured

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Special tools and workshop equipment required

Cylinder Dial Bore Gauge :VAS6078

CAUTION:

- Never handle the cylinder bore with service equipment (drilling, honing, lapping).

-- Using a :VAS6078 measure in a diagonal sequence at three positions transversely -A- and longitudinally -B-.

Deviation from specified size: maximum 0.08 mm

-	-	Cylinder Bore Diameter
Standard dimension	mm	82.51

The cylinder bore must not be measured when the cylinder block is mounted on the :VAS6095A because the measurements may be incorrect.