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.
Spark Plug: Inspection
- Check the spark plug for damage. If defective, replace the spark plug.
- Check the spark plug electrode and condition of the insulator. If abnormal, check and repair the cause and replace the spark plug.CAUTION: Do not use a plug cleaner or brush to clean the spark plug as it may damage the electrode area.
- Normal:
Brown to grayish-tan deposits and slight electrode wear indicate correct spark plug heat range.
- Carbon fouled:
Dry fluffy carbon deposits on the insulator and electrode are mostly caused by slow-speed driving in town, weak ignition, too rich fuel mixture, etc.
- Oil fouled:
Wet black deposits show oil entrance into combustion chamber through worn piston rings or increased clearance between valve guides and valve stems.
- Overheating:
A white or light gray insulator with black or brown spots and bluish burnt electrodes indicate engine overheating, wrong selection of fuel, or loose spark plugs.
- Normal:
- Visually check the spark plug gap (A). If faulty such as deformation is found, replace the spark plug.
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.
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