Piston And Cylinder Bore, Checking

Special tools and workshop equipment required

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.

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

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:

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

-- Using the :VAS6078 , measure in a diagonal sequence at three positions transversely -A- and longitudinally -B-.

Cylinder bore diameter in mm
Specified Size	82.51 ¹⁾ mm
¹⁾ measure 50 mm inside the cylinder bore.

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	Wear limit
1. Compression ring	0.30 to 0.40 mm	0.80 mm
2. Compression ring	0.40 to 0.50 mm	0.80 mm
Two-piece oil scraping ring	0.20 to 0.40 mm	0.80 mm
Three-piece oil scraping ring	Cannot be measured

Fig 2: Checking Piston Ring Groove Clearance

Courtesy of AUDI OF AMERICA, LLC

-- Clean the piston ring groove before checking.