Pistons And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2016 Audi A7 Quattro. However, it is still accessible from the selected car via links, so may be relevant.

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-- Measure approximately 10 mm from the lower edge at a 90° angle to the piston pin axis using a 75 to 100 mm external micrometer.

Maximum deviation from the specified dimension: 0.05 mm.

Matching pistons are allocated to the different dimensions of the cylinder block.

Piston Diameter mm
Specified dimension	82.924 and 82.936 ¹⁾
Repair stage	82.964 to 82.976 ¹⁾
¹⁾ Measurement without coating (thickness = 0.02 mm). The coating wears off partially.

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-- Using the Cylinder Dial Bore Gauge:VAS6078 measure in a diagonal sequence at three positions transversely -A- and longitudinally -B-.

Maximum deviation from the specified dimension: 0.08 mm.

Cylinder Bore Diameter in mm
Specified dimension	83.006 and 83.014 ¹⁾
Repair stage	83.046 to 83.054 ¹⁾
¹⁾ measure 50 mm inside the cylinder bore.

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-- Push the piston ring squarely from above down to approximately 50 mm from the bottom end of the cylinder.

-- To do this use a piston without piston rings.

Piston Ring	New mm	Wear Limit mm
1st Compression ring	0.25 to 0.40	0.60
2nd Compression ring	0.70 to 0.90	1.20
Oil scraping ring	0.25 to 0.50	0.70

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-- Clean the piston ring groove before checking.

Piston Ring	New mm	Wear Limit mm
1st Compression ring	0.09 to 0.13	0.16
2nd Compression ring	0.05 to 0.09	0.11
Oil scraping ring	0.03 to 0.07	0.10