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Lincoln Mark VIII Spark Plug

Common Problems of the Lincoln Mark Viii Spark Plug and How to Spot Them

The Lincoln Mark Viii spark plug has one of the toughest, most crucial jobs in keeping the engine alive and working properly. It produces a hot spark inside the combustion chamber to light up the fuel and air mixture into flames. However, once it starts to wear out, you will experience a sudden drop in engine performance. Ignoring this problem will put a stress on the other components, which will lead to engine failure. If you sense that your vehicle is not working as well as it used to, immediately check the spark plug for any problems such as:

Shunting or shunt firing

"Shunting" is a condition in which a short circuit occurs from lowered shunt resistance. This usually happens when there's a build-up of metallic deposits on the electrodes of an old spark plug. To check the component for any metallic deposits, remove it from the engine using a plug wrench or a ratchet. Then, look closely at the side and central electrodes for any band of materials forming.

Carbon fouling

When the engine starts poorly, the spark plug misfires, or the acceleration becomes faulty, then there must be carbon fouling in your system. When you check the spark plug for this condition, there should be dry, soft black carbon on its insulator and electrodes. Carbon fouling is often caused by faulty chokehold over rich air/fuel mixture, delayed ignition timing, bad ignition leads, or cold plug heat range.


When the plug's insulator is extremely white, has small, black deposits, and with premature electrode erosion, it is highly likely that the spark plug is overheating. Its signs include loss of power at high speeds or when carrying heavy load. Check if the plug is not tightened properly as this might be the cause. The engine might also be insufficiently cooled, the ignition timing too advanced, or the plug heat range might be too hot.

Other symptoms to check

While the spark plug is still out, also check for bent or dented electrodes and a broken insulator as these are already considered as mechanical damages. If the central or ground electrode is melted or burned, the plug might have also been loosely screwed. The spark plug will have to be replaced if either of these is the case.

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  • Tips to Servicing the Lincoln Mark Viii Spark Plug

    The Lincoln Mark Viii spark plug is the reason why your car's engine starts. Because its electrodes produce a powerful spark that's needed for ignition, they should always be kept clean and sharp. When you leave your spark plug worn and unkempt, it will need more electric current to power up the engine adequately. If you haven't tuned your engine for a long time or if you find that you have to tug on the rewind several times in order to start the engine, then the spark plug might be damaged. To avoid this inconvenience, you always have to keep the component--and the rest of your engine--in check.

    When to clean the spark plug

    Your car's spark plug should be inspected and cleaned every 30,000 miles even if your car is considered low maintenance to prevent it from seizing in the block. Meanwhile, when replacing the component, it should be done every 100,000 miles.

    Cleaning the spark slug

    • Remember to identify which spark plug goes with the correct cylinder. Use a system, such as numbering and labeling, to help you with this.
    • Before disconnecting, clean the area around the spark plug using compressed air in order to avoid getting debris in the combustion chamber.
    • Disconnect the spark plug using a spark plug socket before cleaning to avoid possible electrocution or damage of other components. If you don't have this tool yet, buy one that's of deep-well type, and preferably one that has a rubber or magnetic retainer inside. When removing, do not pull on the wire itself; instead, remove the component from the terminal boot.
    • To avoid confusion, use an arrangement technique that can help you easily identify the wire with a certain spark plug. An easy method would be to use a numbered clothespin that could be clipped on the wire.
    • Use a wire brush and a spray-on plug cleaner to clean light deposits from the spark plug. If there are any tough dirt left in the component, use a sturdy knife.
    • If your car's spark plug has a shot blaster or abrasives, do not clean it.
    • If the component still has some deposits left that can't be removed by the knife, then you must replace the spark plug. This is also the case for those with cracked porcelain or burnt electrodes.
    • When reinstalling the spark plug, do not overtighten it--the maximum tightness for a spark plug is 15 ft./lb.