Piston And Cylinder Bore, Checking

Fig 1: Checking Piston

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
Basic dimension	mm	82.465 ¹⁾
¹⁾ Measurements without graphite coating (thickness = 0.02 mm). The graphite coating wears off.

Fig 2: Checking Piston Ring Gap

Courtesy of AUDI OF AMERICA, LLC

-- Push piston ring squarely from above down to approximately 15 mm from bottom end of cylinder. To do this use a piston without rings.

Piston Ring Dimensions in mm	New	Wear Limit
Compression ring	020 to 0.40	0.80
Oil scraping ring	0.25 to 0.50	0.80

Fig 3: Checking Piston Ring Gap

Courtesy of AUDI OF AMERICA, LLC

-- Clean the ring groove of piston before checking.

Fig 4: Checking Cylinder Bores

Courtesy of AUDI OF AMERICA, LLC

Special tools and workshop equipment required

CAUTION:

Do not bore, hone, grind or rework the cylinder bores with workshop tools. Reworking damages the surface of the cylinder bore.

-- Using a VAS 6078 or US1033/S measure in a diagonal sequence at 3 positions transversely -A- and longitudinally -B-.

		Cylinder Bore Diameter
Basic dimension	mm	82.51

NOTE:

Measurement of cylinder bore may not be performed when the cylinder block is mounted in VAS 6095, false measurements are possible.