Chevrolet Silverado / GMC Sierra. Service manual — part 2129

Fig. 60: Measuring Camshaft Runout
Courtesy of GENERAL MOTORS CORP.

12. Measure the camshaft runout.

1. Mount the camshaft in wooden V-blocks or between centers on a fixture.

2. Using the J 7872 , measure the runout of the intermediate camshaft bearing journals.

3. If camshaft runout exceeds 0.05 mm (0.002 in), the camshaft is bent and should be

replaced.

Measuring Camshaft Lobe Lift

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

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. 61: Measuring Camshaft Lobe Lift
Courtesy of GENERAL MOTORS CORP.

1. Using the J 8520 , measure camshaft lobe lift. See Special Tools .

2. Remove the valve rocker arms and bolts.

3. Install the dial indicator mounting stud into the valve rocker arm bolt hole.

4. Assemble the components of the J 8520 and position onto the stud. See Special Tools .

5. Position the shaft of the dial indicator onto the end of the pushrod.

6. Rotate the face of the dial indicator to zero.

7. Slowly rotate the crankshaft clockwise, until the dial indicator obtains its highest and lowest

readings.

8. Compare the total to specifications. 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 LH6 VIN M) or Engine Mechanical Specifications (RPO LMG VIN 0) or
Engine Mechanical Specifications (RPO LY6 VIN K) or Engine Mechanical
Specifications (RPO L76 VIN Y) or Engine Mechanical Specifications (RPO L92
VIN 8) .

CAMSHAFT AND BEARINGS CLEANING AND INSPECTION (RPO LY6/L76/L92)

Tools Required

J 7872 Magnetic Base Dial Indicator Set

J 8520 Camshaft Lobe Lift Indicator. See Special Tools .

Cleaning & Inspection

IMPORTANT: Measuring camshaft lobe lift is a procedure used to

determine if the camshaft lobes have worn. This test is to be
performed prior to engine disassembly and with the camshaft
and valve train components installed in the engine.

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. 62: View Of Camshaft Inspection Points
Courtesy of GENERAL MOTORS CORP.

1. Clean the components in solvent.

2. Dry the components with compressed air.

3. Inspect the camshaft bearing journals (1) for scoring or excessive wear.

4. Inspect the camshaft valve lifter lobes (2) for scoring or excessive wear.

5. Inspect the camshaft position (CMP) actuator oil passages (3) for restrictions.

6. Inspect the threaded bolt hole (4) in the front of the camshaft for damaged threads or debris.

CAUTION: Refer to Safety Glasses and Compressed Air Caution .

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