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.

2001 GMC C3500 HD 8.1 G, AutomaticFACTORY OEM SERVICE PROCEDURE

Ignition System Specifications

Application	Specification
Application	Metric	English
Firing Order	1-8-7-2-6-5-4-3
Spark Plug Wire Resistance	1,000 ohms per ft
Spark Plug Torque	20Y	15 lb ft
Spark Plug Gap	1.52 mm	0.060 in
Spark Plug Type	Refer to Electronic Parts Catalogue

Factory Service Tools

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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.