Pistons And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2018 Audi A6 Quattro, 2017 Audi A6 Quattro, and 2016 Audi A6 Quattro. 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.

Maximum deviation from the nominal dimension: 0.03 mm.

Piston Diameter mm
Specified dimension	84.49 ¹⁾
¹⁾ Measurements with coating (thickness = 0.02 mm). The coating wears off.

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-- Using the :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	84.51 ¹⁾
¹⁾ measure 50 mm inside the cylinder bore.

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-- Push the piston ring squarely from above down to approximately 15 mm from the bottom end of the cylinder.

-- Use a piston without a piston ring for sliding in.

Piston Ring	New mm	Wear Limit mm
1st Compression ring	0.20 to 0.30	0.80
2nd Compression ring	0.50 to 0.70	0.80
Oil Scraping Ring	0.25 to 0.50	- ¹⁾
¹⁾ Not determined yet.

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-- Clean the piston ring groove before checking.

Piston Ring	New mm	Wear Limit mm
1st Compression ring	0.04 to 0.08	0.20
2nd Compression ring	0.03 to 0.07	0.20
Oil Scraping Ring	0.02 to 0.06	0.15