Piston And Cylinder Bore, Checking: Notes

WARNING: This page is about a different car, the 2023 Volkswagen Atlas. However, it is still accessible from the selected car via links, so may be relevant.

Checking the piston ring gap:

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 to the cylinder wall from above down in the lower cylinder opening approximately 15 mm from bottom edge of the cylinder. To push in use a piston without rings.

Piston Ring		Ring Gap
		New	Wear limit
Compression Ring	mm	0.30 to 0.45	1.0
Taper-Faced Napier Ring	mm	0.30 to 0.50	1.0
Oil Scraping Ring	mm	0.20 to 0.90	1.2

Checking the piston ring groove clearance:

Fig 2: Checking Piston Ring Groove Clearance

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required

Feeler Gauge

Test Sequence

Clean the ring groove before checking.

Piston Ring		Ring to groove clearance
		New	Wear limit
Compression Ring	mm	0.04 to 0.06	0.12
Taper-Faced Napier Ring	mm	0.03 to 0.06	0.15
Oil Scraping Ring	mm	0.02 to 0.06	0.15

Checking the pistons:

Fig 3: Checking Piston Bore

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required

Outside Micrometer - 75-100mm:VAS 6071

Test Sequence

-- Take a measurement approximately 15 mm from lower edge and offset 90° to the piston pin axis.

Maximum difference from specified size: 0.06 mm