Hummer H2. Manual — part 1875

Fig. 654: Valve Rocker Arms
Courtesy of GENERAL MOTORS CORP.

5. Install the rocker arms and bolts.

IMPORTANT:

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Ensure that the pushrods seat properly to the ends of the rocker
arms.

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DO NOT tighten the rocker arm bolts at this time.

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 655: View Of Crankshaft
Courtesy of GENERAL MOTORS CORP.

6. Rotate the crankshaft until number one piston is at top dead center of compression stroke.

In this position, cylinder number one rocker arms will be off lobe lift, and the crankshaft sprocket key

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

will be at the 1:30 position. If viewing from the rear of the engine, the additional crankshaft pilot hole,
non-threaded, will be in the 10:30 position.

The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3.

Cylinders 1, 3, 5 and 7 are left bank.

Cylinders 2, 4, 6, and 8 are right bank.

7. With the engine in the number one firing position, tighten the following valve rocker arm bolts:

Tighten:

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Tighten exhaust valve rocker arm bolts 1, 2, 7, and 8 to 30 N.m (22 lb ft).

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Tighten intake valve rocker arm bolts 1, 3, 4, and 5 to 30 N.m (22 lb ft).

8. Rotate the crankshaft 360 degrees.

9. Tighten the following valve rocker arm bolts:

Tighten:

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Tighten exhaust valve rocker arm bolts 3, 4, 5, and 6 to 30 N.m (22 lb ft).

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Tighten intake valve rocker arm bolts 2, 6, 7, and 8 to 30 N.m (22 lb ft).

VALVE ROCKER ARM COVER INSTALLATION - LEFT

NOTE:

Refer to Fastener Notice in Cautions and Notices.

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 656: Valve Rocker Arm Cover Gasket
Courtesy of GENERAL MOTORS CORP.

1. Install a NEW cover gasket (504) into the left valve rocker arm cover.

IMPORTANT:

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All gasket surfaces should be free of oil or other foreign material
during assembly.

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DO NOT use the valve rocker arm cover gasket again.

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The valve rocker arm cover bolt grommets may be used again.

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If the vapor vent grommet has been removed from the valve rocker
arm cover, install a NEW vapor vent gourmet during assembly.

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2