Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2003 Hummer H2 V8-6.0LFACTORY OEM SERVICE PROCEDURE
Spark Plug: Service and Repair
SPARK PLUG REPLACEMENT
REMOVAL PROCEDURE
1. Remove the spark plug wires.
2. Loosen each spark plug 1 or 2 turns.
3. Brush or air blast away any dirt from around the spark plugs.
4. Remove the spark plugs 1 at a time. Place each plug in a tray marked with the corresponding cylinder numbers.
INSTALLATION PROCEDURE
1. Properly position each spark plug washer.
2. Inspect each spark plug gap. Adjust each plug as needed.
Specification
Spark plug gap: 1.02 mm (0.040 in)
NOTE: Refer to Fastener Notice in Service Precautions.
3. Hand start the spark plugs in the corresponding cylinders.
4. Tighten the spark plugs.
Tighten
- For used heads tighten the spark plugs to 15 N.m (11 lb ft).
- For new aluminum heads tighten the spark plugs to 20 N.m (15 lb ft).
- For new iron heads, tighten the spark plugs to 30 N.m (22 lb ft).
5. Install the spark plug wires.
REMOVAL PROCEDURE
1. Remove the spark plug wires.
2. Loosen each spark plug 1 or 2 turns.
3. Brush or air blast away any dirt from around the spark plugs.
4. Remove the spark plugs 1 at a time. Place each plug in a tray marked with the corresponding cylinder numbers.
INSTALLATION PROCEDURE
1. Properly position each spark plug washer.
2. Inspect each spark plug gap. Adjust each plug as needed.
Specification
Spark plug gap: 1.02 mm (0.040 in)
NOTE: Refer to Fastener Notice in Service Precautions.
3. Hand start the spark plugs in the corresponding cylinders.
4. Tighten the spark plugs.
Tighten
- For used heads tighten the spark plugs to 15 N.m (11 lb ft).
- For new aluminum heads tighten the spark plugs to 20 N.m (15 lb ft).
- For new iron heads, tighten the spark plugs to 30 N.m (22 lb ft).
5. Install the spark plug wires.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.