Piston And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2024 Audi RS 3. 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 OF AMERICA, LLC

-- Measure approximately 10 mm from the lower edge at a 90° angle to the piston pin axis using a 75 to 100 mm outside micrometer.

Maximum difference from specified size: 0.06 mm

		Piston diameter
Standard dimension	mm	82.444 ¹⁾

Piston Ring Gap, Checking

Fig 2: 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.

-- Measure with feeler gauge.

Piston ring dimensions in mm	New	Wear limit
1. Compression ring	0.20 to 0.30	0.50
2. Compression ring	0.35 to 0.55	0.75
Three-piece oil scraping ring	cannot be measured

Cylinder Bore, Checking

Fig 3: Checking Cylinder Bore (Dimensions)

Courtesy of AUDI OF AMERICA, LLC

Special tools and workshop equipment required

Cylinder Dial Bore Gauge :VAS 6078

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

Maximum deviation from the specified size: 0.03 mm.

		Cylinder bore diameter
Standard dimension	mm	82.51

The measurement can only be performed with the tensioning plate installed, because the incorrect measurement is possible.
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.