Pistons And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2015 Volkswagen Beetle. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Checking Pistons

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- 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.

Maximum deviation from nominal dimension: 0.04 mm

NOTE:

Check for wear on the piston shaft-coating and general coking.

A piston must be replaced if there are cracks on the piston shaft.

Piston diameter mm
Nominal dimension	80.92 ¹⁾
¹⁾ Measurement with coating (thickness = 0.02 mm). The coating wears off.

Fig 2: Checking Cylinder Bores

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Using a Cylinder Dial Bore GaugeVAS6078 measure in a diagonal sequence at three positions transversely -A- and longitudinally -B-.

Maximum deviation from nominal dimension: 0.10 mm.

NOTE:

Pay attention to scratches and other abnormalities on the cylinder wall.

Cylinder Bore Diameter in mm
Nominal dimension	81.03

NOTE:

The cylinder bore must not be measured when the cylinder block is mounted on the Engine and Transmission HolderVAS6095 because the measurements may be incorrect.

Fig 3: Checking Piston Ring Gap

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- 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.

Piston Ring	New mm	Wear limit mm
1. Compression ring	0.30 to 0.40	0.55
2. Compression ring	0.20 to 0.45	0.95
Oil scraping ring	0.25 to 0.50	0.75

Fig 4: Checking the Piston Ring Groove Clearance

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Clean the piston ring groove before checking.

Piston Ring	New mm	Wear Limit mm
1. Compression ring	0.06 to 0.09	0.08
2. Compression ring	0.05 to 0.08	0.08
Oil scraping ring	0.03 to 0.06	0.08