Piston, Rings And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2008 Volkswagen R32. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Checking Piston Ring Gap

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required

Feeler gauge

Test Sequence

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

Piston ring		Gap
		New	Wear limit
Compression ring	mm	0.20 to 0.40	1.0
Tapered ring	mm	0.20 to 0.40	1.0
Oil scraping ring	mm	0.25 to 0.50	1.0

Fig 2: Checking Piston Ring Gap

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required

Feeler gauge

-- Clean the ring grooves before checking.

Piston ring		Ring to groove clearance
		New	Wear limit
Compression ring	mm	0.04 to 0.09	0.15
Tapered ring	mm	0.03 to 0.06	0.15
Oil scraping ring	mm	0.02 to 0.06	0.15

Fig 3: Checking Piston

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required

External micrometer 75 to 100 mm

-- Take the measurement approximately 6 mm from the lower edge of the piston skirt and offset 90 degrees to the piston axis.

Deviations from nominal dimension: 0.04 mm

Fig 4: Checking Cylinder Bore

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required

Internal dial gauge 50 to 100 mm

Test Sequence

-- Measure diagonally at 3 positions transversely -A- and longitudinally -B-.

Deviations from nominal dimension: 0.08 mm.

NOTE:

The measurement of the cylinder bore may not be performed when the cylinder block is mounted on the engine and transmission holder VAS 6095 or the holding fixture VW 540, false measurements are possible.