F 350 2WD Super Duty V10-6.8L VIN S (1999)
6. Inspect for normal burning.
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Check for light tan or gray deposits on the firing tip.
7. Inspect for pre-ignition.
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Identified by melted electrodes and possibly blistered insulator.
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Metallic deposits on the insulator indicate engine damage.
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May be caused by incorrect ignition timing, wrong type of fuel, or the installation of a heli-coil in place of spark plug threads.
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Replace the spark plug.
8. Inspect for overheating.
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Identified by a white or light gray insulator with small black or gray brown spots and with bluish-burnt appearance of electrodes.
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Caused by engine overheating, wrong type of fuel, loose spark plugs, plug with incorrect heat range, low fuel pump pressure, or incorrect
timing.
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Replace the spark plug.
9. Inspect for fused spot deposits.
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Identified by melted or spotty deposits resembling bubbles or blisters.
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Caused by sudden acceleration.
