Piston, Pistons Rings And Cylinder Bore, Checking

WARNING: This page is about a different variant/trim than selected.

Fig 1: 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.

-- To do this use a piston without piston rings.

-- Measure with feeler gauge.

Piston Ring Dimensions in mm	New	Wear Limit
Compression ring	0.20 to 0.40	0.8
Oil scraping ring	0.25 to 0.55	0.8

Fig 2: Checking Piston Ring Gap

Courtesy of AUDI OF AMERICA, LLC

-- Clean piston ring groove.

-- Measure with feeler gauge.

Piston Ring Dimensions in mm	New	Wear Limit
Compression ring	0.035 to 0.075	0.015
Oil scraping ring	0.03 to 0.06	0.15

Fig 3: Checking Piston

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 external micrometer.

Piston Diameter

Basic dimension

82.465 ⁽¹⁾

⁽¹⁾	Measurement without graphite coating (0.02 mm thick). The graphite coating wears off.

Fig 4: Checking Cylinder Bores

Courtesy of AUDI OF AMERICA, LLC

Special tools and workshop equipment required

NOTE:

A shadow or a shiny spot on the wall of the cylinder does not mean the cylinder bore is damaged as long as the cross-grinding is still visible.

Always measure the cylinder bore in 3 places laterally and longitudinally using VAS 6078 or US1033/S.

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

		Cylinder Bore Diameter
Basic dimension	mm	82.51