Pistons And Cylinder Bore, Checking

WARNING: This page is about a different car, the 2012 Audi Q5, 2011 Audi Q5, 2010 Audi Q5, and 2009 Audi Q5. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Checking Pistons

Courtesy of AUDI OF AMERICA, LLC

-- 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.

		Piston Diameter
Basic dimension	mm	84.49 ¹⁾
¹⁾ Measurement with coating (thickness = 0.02 mm). The coating wears off.

Fig 2: 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.

-- Use a piston without a piston ring for sliding in.

Piston Ring	New Mm	Wear Limit mm
1st Compression ring	0.35 to 0.50	0.8
2nd Compression ring	0.60 to 0.80	1.0
Oil scraping ring	0.25 to 0.50	0.8

Fig 3: Checking Piston Ring Groove Clearance

Courtesy of AUDI OF AMERICA, LLC

-- Clean the piston ring groove before checking.

Piston Ring	New Mm	Wear Limit mm
Compression rings	0.02 to 0.08	0.20
Oil scraping ring	0.02 to 0.08	0.15

Fig 4: Checking Cylinder Bores

Courtesy of AUDI OF AMERICA, LLC

Special tools and workshop equipment required

Cylinder Dial Bore Gauge VAS6078

-- Using a Cylinder Dial Bore Gauge VAS6078 measure in a diagonal sequence at three positions transversely -A- and longitudinally -B-.

Maximum deviation from the specified dimension: 0.08 mm.

		Cylinder Bore Diameter
Basic dimension	mm	84.51