Chevrolet Silverado / GMC Sierra. Manual — part 578

Courtesy of GENERAL MOTORS CORP.

3. Measure the piston ring end gap.

Use a piston to square the piston ring near the top of the cylinder.

Use a feeler gauge to measure the piston ring gap.

The 1st compression ring production gap is 0.30-0.45 mm (0.0118-0.0177 in) and the
service limit is 1.37 mm (0.0539 in).

The 2nd compression ring production gap is 0.50-0.65 mm (0.0197-0.0256 in) and the
service limit is 1.35 mm (0.0531 in).

The oil ring production gap is 0.15-0.35 mm (0.0059-0.0138 in) and the service limit
is 1.20 mm (0.0472 in).

Replace the piston ring if the measured value exceeds the service limit.

Fig. 4: Measuring Piston Ring Side Clearance
Courtesy of GENERAL MOTORS CORP.

4. Measure the piston ring to piston ring groove clearance.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Use a feeler gauge to measure the clearance between the piston ring and the piston ring
groove at several points around the piston.

The 1st compression ring production clearance is 0.08-0.17 mm (0.0030-0.0007 in)
and the service limit is 0.26 mm (0.0102 in).

The 2nd compression ring production clearance is 0.01-0.03 mm (0.0004-0.0012 in)
and the service limit is 0.10 mm (0.0039 in).

The oil ring production clearance is 0.01-0.03 mm (0.0004-0.0012 in) and the service
limit is 0.12 mm (0.0047 in).

Replace the piston ring if the measured value exceeds the service limit.

Fig. 5: Measuring Piston Pin Diameter
Courtesy of GENERAL MOTORS CORP.

5. Measure the piston pin outside diameter.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Measure the piston pin outside diameter at several points.

The production value is 34.495-34.50 mm (1.3581-1.3563 in) and the service limit is
34.450 mm (1.3563 in).

Replace the piston pin if the measured value is less than the service limit.

Fig. 6: Measuring Piston Pin Bore
Courtesy of GENERAL MOTORS CORP.

6. Measure the piston pin to piston pin bore clearance.

Measure the piston pin bore.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado