Chevrolet Silverado / GMC Sierra. Service manual — part 365

1. Inspect the CMP valve for the following conditions:

Dirt, debris, or restrictions within the oil passages (1)

Damaged threads (2)

If the threads of the valve are damaged, also inspect the threads in the front of the
camshaft for damage.

Dirt, debris, or restrictions within the oil inlet check valve (3)

If debris is detected, the engine assembly should be inspected to determine the source
of contamination.

diagnostic purposes only.

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2

Fig. 467: View Of Proper Valve Spool Position
Courtesy of GENERAL MOTORS CORP.

2. Inspect for a sticking valve spool or broken valve spool spring.

3. Depress the valve spool into the housing. The valve should move freely with no binding or

sticking and minimal resistance inward. When released, the valve spring should return the
spool to the proper extended position (1) of 6.08-6.12 mm (0.239-0.241 in).

VALVE ROCKER ARM AND PUSH ROD CLEANING AND INSPECTION

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2

Fig. 468: Identifying Valve Rocker Arm Components
Courtesy of GENERAL MOTORS CORP.

1. Mark, sort, or organize the components for assembly. Refer to Separating Parts.

2. Clean the components with cleaning solvent.

IMPORTANT: Parts that are to be used again must be marked, sorted or

organized for assembly.

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2

3. Dry the components with compressed air.

4. Inspect the valve rocker arms bearings (2) for binding or roughness.

5. Inspect the valve rocker arm pushrod sockets (3) and valve stem mating surfaces (1). These

surfaces should be smooth with no scoring or exceptional wear.

6. Inspect the pushrods for worn or scored ends. These surfaces should be smooth with no

scoring or exceptional wear.

7. Inspect the pushrods for bends. Roll the pushrod on a flat surface to determine if the pushrod

is bent.

8. Inspect the pushrod oil passages for restrictions.

9. Inspect the rocker arm pivot supports for cracks, wear, or other damage.

VALVE LIFTERS AND GUIDES CLEANING AND INSPECTION

Valve Lifters

CAUTION: Refer to Safety Glasses and Compressed Air Caution .

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2