Chevrolet Silverado / GMC Sierra. Service manual — part 2114

Fig. 12: Crankshaft Bearing Polished Sections (Improper Seating)
Courtesy of GENERAL MOTORS CORP.

17. Inspect the crankshaft bearings for improper seating, indicated by bright, polished sections

of the bearing.

If the lower half of the bearing is worn or damaged, both upper and lower halves should be
replaced.

Generally, if the lower half is suitable for use, the upper half should also be suitable for use.

Measuring Main Bearing Clearance - Gaging Plastic Method

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

Fig. 13: View Of Gaging Plastic Installed On Crankshaft Journal
Courtesy of GENERAL MOTORS CORP.

IMPORTANT:

The crankshaft main bearings are a precision insert
type. Main bearing caps are machined with the engine
block, for proper clearance, and cannot be shimmed or
filed for bearing fit. If the clearances are found to be
excessive, new bearings and/or engine block and cap
repair or replacement may be required.

Do not rotate the crankshaft while gaging plastic is
between the crankshaft journal and the bearing surface.

The crankshaft bearing clearances are critical.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

1. Remove the bearing caps, bearing half, and bolts. Refer to Crankshaft and Bearing

Removal .

2. Install gaging plastic onto the crankshaft journal. Install the gaging plastic the full width of

the crankshaft bearing journal.

3. Install the bearing caps, bearing half, and bolts. Refer to Crankshaft and Bearing

Installation.

4. Remove the bearing caps, bearing half, and bolts. Refer to Crankshaft and Bearing

Removal .

Excessive bearing clearance may affect crankshaft
position sensor signals and may affect OBD II system
operation.

Remove the bearing cap side bolts prior to cap removal.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

Fig. 14: Measuring Gaging Plastic
Courtesy of GENERAL MOTORS CORP.

5. Using the scale supplied with the plastic gaging kit, measure the gaging plastic at its widest

area.

If the gaging plastic shows irregularity in the journal, exceeding 0.025 mm (0.001 in),
remove the crankshaft and measure the journal with a micrometer.

If clearance cannot be brought to specifications, replace the crankshaft or engine block
as required. Refer to Engine Mechanical Specifications (RPO LY5 VIN J) or
Engine Mechanical Specifications (RPO LC9 VIN 3) or Engine Mechanical
Specifications (RPO LY2 VIN C) or Engine Mechanical Specifications (RPO

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado