Pistons And Cylinder Bore, Checking

Fig 1: Checking Pistons

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 mm
Specified dimension	84.49 ¹⁾
¹⁾ Measurement with coating (thickness = 0.02 mm). The coating wears off.

Fig 2: Checking Cylinder Bores

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-- Using the Cylinder Dial Bore Gauge VAS6078 measure in a diagonal sequence at three positions transversely -A- and longitudinally -B-.

Cylinder Bore Diameter in mm
Specified dimension	84.51 ¹⁾
¹⁾ Measure 50 mm inside the cylinder bore.

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 bottom end of the cylinder.

-- Use a piston without a piston ring for sliding in.

Fig 4: Checking Piston Ring Groove Clearance

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-- Clean the piston ring groove before checking.