Piston And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2024 Audi Q3 and 2023 Audi Q3. However, it is still accessible from the selected car via links, so may be relevant.

Pistons, Checking

Fig 1: Checking Piston Bore

Courtesy of AUDI

-- 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 variance from the specified size: 0.04 mm.

Piston Diameter in mm
Specified size	82.42 ¹⁾
¹⁾ Measurement without coating (thickness = 0.02 mm). The coating wears off.

Cylinder Bore, Checking

Fig 2: Checking Cylinder Bore (Dimensions)

Courtesy of AUDI

Special tools and workshop equipment required

Cylinder Dial Bore Gauge:VAS 6078

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).

-- Using the Cylinder Dial Bore Gauge:VAS 6078 , measure in a diagonal sequence at three positions transversely -A- and longitudinally -B-.

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

-- 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	0.80
2. Compression ring	0.40 to 0.50	0.80
Two-piece oil scraping ring	0.20 to 0.40	0.80
Three-piece oil scraping ring	cannot be measured

Piston Ring Groove Clearance, Checking

Fig 4: Checking Piston Ring Groove Clearance

Courtesy of AUDI

-- Clean the piston ring groove before checking.

Piston Ring in Connection with the Two-Piece Oil Scraping Ring	New mm	Wear Limit mm
1. Compression ring	0.06 to 0.09	0.20
2. Compression ring	0.03 to 0.06	0.15
Oil scraping rings	cannot be measured