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Reading Spark Plugs

If your spark plugs space fouled or damaged, it can lead come a host of troubles including diminished gas mileage, slow acceleration, engine misfires and trouble beginning the engine. If you room experiencing engine problems, taking a look at your spark plugs is a great place to start. Once reading spark plugs, you will likely discover one of the adhering to conditions:

NormalCarbon fouledOil depositsWetBurnedWorn electrodesBroken electrodes

Checking the power of your Engine

Examining your engine’s spark plugs can provide you an idea of exactly how the engine is running. You have the right to do this as component of the routine maintenance of your car, ATV, lawnmower or boat, or if you suspect something is wrong with the engine.

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Getting Started


The an initial step is removed the spark plug you want to watch at. Follow these instructions on just how to remove a spark plug. Take it the spark plug in your hand and also begin looking in ~ it for indicators of damage. Look at finish of the spark plug that remained in the cylinder and examine it. You will likely see among the following conditions.

Normal spark plug


A typical spark plug will have brown or grayish-tan shop on the side electrode. Everything is just fine through your spark plug; you can reinstall the spark plug.

Carbon fouled


Black, dry soot on the electrodes and also insulator tip suggests a carbon-fouled plug. This can be resulted in by a dirty wait filter, extreme driving at short speeds, too rich of a fuel/air mixture or idling your auto for too long. Your mechanic can offer you advice top top what form of spark plug to buy to replace the damaged plug, yet you may want to think about switching to a “hotter” spark plug (the higher the spark plug number, the hotter the plug).

Oil deposits


Black, oily store on the electrodes and also insulator guideline points come an oil-fouled plug. Oil can be leaking right into the cylinders, getting past pistons that are worn or valve travel guide that are worn. Recognize the resource of the leak is really important – consult a mechanic because that guidance. When the difficulty is addressed, you can replace the spark plug.


A wet spark plug deserve to be the an outcome of the engine flooding. Flooding is what happens when you try to begin the engine numerous times without it shoot up. You deserve to clean the spark plugs or you have the right to just wait because that them to dry out.


Blisters on the insulator tip, melted electrodes, or white deposits are indications of a shed spark plug that is running also hot. Reasons can incorporate the engine overheating, not correct spark plug heat range, a loose spark plug, not correct ignition timing or as well lean of one air/fuel mixture. The spark plug need to be replaced.

Worn electrodes

Worn and eroded electrodes space symptoms that a spark plug that is past its prime. The plug has been in the engine also long and also needs to be replaced.

Broken electrodes

If the electrodes are damaged off or flattened, it is most likely that the not correct spark plugs room installed. A spark plug the is too long can cause extensive damages to your engine while a short spark plug have the right to cause poor gas mileage and also spark plug fouling. Inspect your owner’s hand-operated to ensure that you have the correct spark plug for her vehicle.

What’s next?

If you have identified that you have the right to reinstall the spark plug or room installing a new one, follow these instructions. You deserve to then proceed to study your spark plugs, one at a time. If your spark plugs need replacing, you deserve to tackle it you yourself or if you feel you need more assistance, call your reliable mechanic.


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