Piston And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2022 Audi A6 Quattro and 2021 Audi A6 Quattro. However, it is still accessible from the selected car via links, so may be relevant.

Special tools and workshop equipment required

Outside Micrometer - 75-100mm: VAS6071
Internal Dial Gauge: VAS6078

Pistons, Checking

Fig 1: Checking Piston Bore

Courtesy of AUDI OF AMERICA, LLC

-- Measure approximately 15 mm from the lower edge at a 90° angle to the piston pin axis using : VAS6071 .

Maximum variance from the specified size: 0.04 mm.

Piston Diameter in mm
Specified size	82.420 ¹⁾
¹⁾ Measurement without coating (thickness = 0.04 mm). The coating wears off.

Cylinder Bore, Checking

Fig 2: Cylinder Bore, Checking

Courtesy of AUDI OF AMERICA, LLC

The cylinder bore must not be measured when the cylinder block is mounted on the engine and transmission holder because the measurements may be incorrect.

CAUTION:

Risk of damaging the cylinder bore surface through incorrect handling.

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

-- Measure at three locations -c-, in longitudinal direction -a- and cross direction -b- using the : VAS6078 .

Maximum variance from the specified size 0.08 mm.

Cylinder Bore Diameter in mm
Specified size	82.51 ¹⁾
¹⁾ measure 50 mm inside the cylinder bore.

Piston Ring Gap, Checking

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 edge of the cylinder. To push in use a piston without rings.

Piston Ring	New mm	Wear Limit mm
1. Compression ring	0.30 to 0.40	0.60
2. Compression ring	0.40 to 0.50	0.70
Oil Scraping Ring	cannot be measured