Hummer H2. Manual — part 1472

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Ensure that the spark plug has the correct heat range. An incorrect heat range causes the following
conditions:

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Spark plug fouling-Colder plug

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Pre-ignition causing spark plug and/or engine damage-Hotter plug

Spark Plug Inspection

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Introduction) - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 165: Inspecting Spark Plug Components
Courtesy of GENERAL MOTORS CORP.

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Inspect the terminal post (1) for damage.

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Inspect for a bent or broken terminal post (1).

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Test for a loose terminal post (1) by twisting and pulling the post. The terminal post (1) should
NOT move.

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Introduction) - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 166: Inspecting Spark Plug Insulator For Soot
Courtesy of GENERAL MOTORS CORP.

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Inspect the insulator (2) for flashover or carbon tracking, soot. This is caused by the electrical charge
traveling across the insulator (2) between the terminal post (1) and ground. Inspect for the following
conditions:

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Inspect the spark plug boot for damage.

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Inspect the spark plug recess area of the cylinder head for moisture, such as oil, coolant, or water. A
spark plug boot that is saturated causes arcing to ground.

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Introduction) - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 167: Inspecting Spark Plug Insulator
Courtesy of GENERAL MOTORS CORP.

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Inspect the insulator (2) for cracks. All or part of the electrical charge may arc through the crack instead
of the electrodes (3, 4).

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Introduction) - 4.8L, 5.3L, and 6.0L - Hummer H2