Spark Plug: Service and Repair

REMOVAL







1. Disconnect the ignition wires from the spark plugs.







2. Remove and inspect the spark plugs; refer to Steps 3-9.

NOTE:
- If an original spark plug is reused, replace it in the same cylinder from which it was removed. Replacement spark plugs can be used in any cylinder.
- Use compressed air to remove any debris from the spark plug well before removing the spark plugs.







3. Deposits bridging the spark plug gap are caused by oil or carbon fouling. Clean these spark plugs if the deposits are not excessive.







4. Oil-Fouled spark plugs are caused by worn pistons, piston rings, valve guides and, stems and loose bearings. Replace these spark plugs once the oil fouling condition has been corrected.







5. Carbon-fouled spark plugs are caused by a fuel mixture that is too rich. These spark plugs can be cleaned.







6. Overheating damaged spark plugs are caused by engine overheating, incorrect ignition timing, or incorrect spark plugs. Replace these spark plugs once the overheating condition is corrected.







7. Normal spark plugs have light tan or gray deposits on them.







8. Pre-ignition damaged spark plugs are caused by incorrect ignition timing, engine overheating, burnt valves, or the wrong type of fuel. Replace these spark plugs once the pre-ignition condition is corrected.







9. Fused spot deposit spark plugs are caused by sudden acceleration. Clean the spark plugs if the deposits are not excessive.
10. Clean the spark plugs with a wire brush or a professional spark plug cleaner (follow the tool manufacturer's instructions).

INSTALLATION







1. Adjust the spark plug gap as required.
2. Install the spark plug.

NOTE: If an original spark plug is reused, replace it in the same cylinder from which it was removed. Replacement spark plugs can be used in any cylinders.

3. Install the ignition wires.
4. Tighten the spark plugs.