Piston And Cylinder Bore, Checking, Engine Codes CHHB, CNTA, CXCA, CXDA, CXCB And CXDB

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Special tools and workshop equipment required

Outside Micrometer - 75-100mm: VAS6071

Pistons, Checking

Fig 1: Checking Piston Bore

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Measure approximately 15 mm in from the lower edge at a 90° angle to the piston pin axis using a micrometer.

Deviation from specified size: maximum 0.04 mm

Standard Dimension		Piston Diameter
in mm		82.42 ¹⁾
¹⁾ Measurements without graphite coating (thickness = 0.02 mm). The graphite coating wears off.

Piston Ring Gap, Checking

Fig 2: Checking Piston Ring Gap

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required

Feeler Gauge

-- Push the piston ring squarely from above down to approximately 15 mm from the edge of the cylinder. To push in use a piston without rings.

Piston Ring Dimensions in mm	New	Wear Limit
1. Compression ring	0.30 to 0.40	0.80
2. Compression ring	0.40 to 0.50	0.80
Oil Scraping Ring	0.20 to 0.40	0.80

Piston Ring Groove Clearance, Checking

Fig 3: Checking Piston Ring Groove Clearance

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required

Feeler Gauge

-- Clean the piston ring groove before checking.

Piston Ring Dimensions in mm	New	Wear Limit
1. Compression ring	0.06 to 0.09	0.20
2. Compression ring	0.03 to 0.06	0.15
Oil scraping rings	cannot be measured

Cylinder Bore, Checking

Fig 4: Checking Cylinder Bore (Dimensions)

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

NOTE:

The cylinder bore must not be measured when the cylinder block is mounted on the : VAS6095 because incorrect measurement is possible.

Special tools and workshop equipment required

Cylinder Dial Bore Gauge: VAS6078

NOTE:

Risk of damaging the cylinder bore surface through incorrect handling.

Never handle the cylinder bore with service equipment (drilling, honing, grinding).

-- Using a : VAS6078 measure in a diagonal sequence at three positions transversely -A- and longitudinally -B-.

Deviation from specified size: maximum 0.08 mm

Standard Dimension		Cylinder Bore Diameter
in mm		82.51