Piston And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2023 Audi S3, 2023 Audi RS 3, 2023 Audi A3 Quattro, and 2023 Audi A3. 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:VAS 6071

Courtesy of AUDI OF AMERICA, LLC
Internal Dial Gauge:VAS 6078 , not illustrated

Pistons, Checking

Courtesy of AUDI OF AMERICA, LLC

-- Measure approximately 15 mm from the lower edge at a 90° angle to the piston pin axis using Outside Micrometer - 75-100mm:VAS 6071 .

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

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, grinding).

-- Measure at three locations -c-, in longitudinal direction -a- and cross direction -b- using the Internal Dial Gauge:VAS 6078 .

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 1: Piston Ring Gap, Checking

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