Piston And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2012 Audi S5, 2011 Audi S5, and 2010 Audi S5. However, it is still accessible from the selected car via links, so may be relevant.

Special tools and workshop equipment required

Cylinder Gauge VAS 6078 or Inside Micrometer Set 18-100 mm US1033/S

Fig 1: Checking Piston

Courtesy of AUDI OF AMERICA, LLC

-- 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 nominal dimension: 0.03 mm.

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

Fig 2: Checking Cylinder Bores

Courtesy of AUDI OF AMERICA, LLC

-- Measure in a diagonal sequence at 3 positions transversely -A- and longitudinally -B- using a VAS 6078 or US1033/S.

Maximum deviation from nominal dimension: 0.08 mm.

Cylinder Bore Diameter mm
Nominal dimension	84.51 ¹⁾
¹⁾ Measure 50 mm inside the cylinder bore.

Fig 3: Checking Piston Ring Gap

Courtesy of AUDI OF AMERICA, LLC

-- 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.

Fig 4: Checking Piston Ring Side Clearance

Courtesy of AUDI OF AMERICA, LLC

-- 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