Chevrolet Silverado / GMC Sierra. Service manual — part 573

4. Measure the crankshaft journal diameter across four points.

The crankshaft journal outside diameter is 79.905-79.925 mm (3.1459-3.1466 in) and
the service limit is 79.89 mm (3.1453 in).

Replace the crankshaft if the measured value is less than the service limit.

5. Measure the crankpin outside diameter across four points.

The crankpin outside diameter is 62.902-62.922 mm (2.4765-2.4772 in) and the
service limit is 62.88 mm (2.4756 in).

Replace the crankshaft if the measured value is less than the service limit.

Crankshaft Bearing Selection

There are two methods for selecting the proper size crankshaft bearings. The first one is to select
the bearing grade (color code) based on the cylinder block grade and the crankshaft journal grade
from the Crankshaft Bearing Grade chart. The second is the plastic gauge method.

Crankshaft Bearing Selection Grade Chart Method

Stamp ID

Main Journal

Conn. Rod Journal

No Stamp

STD

STD

M20 R20

0.020 in

0.020 in

2008 Chevrolet Silverado 1500

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

Fig. 178: Locating Crankshaft Stamping Marks (Undersized Main or Rod Journals)
Courtesy of GENERAL MOTORS CORP.

1. Inspect the crankshaft for stamping (1) indicating undersized main and/or rod journals.

IMPORTANT: All crankshafts that have been machined have a steel

stamping (1) on the 1st counterweight.

2008 Chevrolet Silverado 1500

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

Fig. 179: View Of Cylinder Block Grade
Courtesy of GENERAL MOTORS CORP.

2. The cylinder block grade is indicated on the right lower portion of the cylinder block.

2008 Chevrolet Silverado 1500

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

Fig. 180: View of Crankshaft Journal Grade
Courtesy of GENERAL MOTORS CORP.

3. The crankshaft journal grade is indicated on the number 1 crankshaft counterweight.

4. Match the cylinder block grade and the crankshaft journal grade, refer to Crankshaft

Bearing Selection Specifications .

2008 Chevrolet Silverado 1500

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