6 Unmistakable Visual Signs: What Do Bad Spark Plugs Look Like? 

Worn and damaged spark plugs could also cause severe problems, which, if left untreated, might cost thousands of dollars to repair. But how to tell if a spark plug is bad? What do bad spark plugs look like? 

If you’re looking for telltale visual signs, this Driverevolve post is precisely what you are after!   

What Do Bad Spark Plugs Look Like?

Checking the spark plugs should be the first thing you do if your engine is giving you trouble. The following are some problems you may find when examining spark plugs:

Carbon Fouled

Your plug gets carbon fouled if you see carbon condensation on your electrodes and insulating tips. A dirty air filtration system, extended idle time, traveling at slow speeds, or an overly rich fuel/air ratio can all contribute to this problem.

You should ask a professional for advice before replacing a spark plug; however, you might want to try upgrading to “hotter” spark plugs (the greater the spark plug number, the hotter it is).

Oil Deposits

Indicators of an oil-fouled plug include black, greasy coatings on its electrodes and insulator tips. Damaged or old valves or nozzle tips could be the reason for the oil in spark plug well.

Seek the advice of a service engineer in identifying the leak’s origin. Once the issue has been fixed, you can change the spark plugs.

Wet

An equally common scenario is the spark plug’s inability to dislodge from oil after being in the water for an extended period. Upon closer inspection, you’ll see that the spark plugs are slowly accumulating water and adapting new shades.

Ingress of spark plugs is unavoidable. Raindrops will find their way into the motor and corrode your spark plugs if you usually drive your car in wet weather. 

Long-term exposure to moisture will cause this component to oxidize, making it unusable. Professionals will usually clean the spark plugs or just allow them to air dry.

Burned

Because of their importance in sparking gasoline, spark plugs are frequently exposed to extreme temperatures. In other words, a fire is inevitable if this component fails to function correctly.

The improper installation of this component might be the root of spark plug fires. Indeed, the car’s ignition mechanism will malfunction if the spark plugs are too loose. Furthermore, the timing of these 2 components’ operations would be off.

An overheated engine is another potential source of spark plug fires. To keep the engine running at peak performance, your spark plugs must constantly ignite gasoline, which might cause excessive heat.

Symptoms of an overheated spark plug include blistering on the insulator tips, burnt electrodes, or white accumulations. If that’s the case, it’s time to get a new spark plug.

Worn Electrodes

Electrode degradation is not a result of environmental factors.  This is mainly because your spark plugs have been in service for too long and should be replaced.

Whenever there is significant corrosion on your plugs, it will be obvious. All of the coils are going black, and the ends have begun to oxidize. When spark plugs wear out, they no longer function correctly and must be replaced soon.

Broken Electrodes

Damaged or flattened electrodes indicate that you’ve used improper spark plugs. 

Too small of a spark plug may reduce fuel efficiency and lead to corrosion, while too big might cause severe damage to the motor. You should confirm your spark plug’s compatibility with your car by checking the manual.

6 Bad Spark Plug Symptoms Everyone Should Know 

If you suspect that you have a bad spark plug but want more signs than just visual clues, refer to the 6 symptoms below.

Engine Misfires

When the air/fuel ratio within the piston is not ignited correctly, an engine misfire occurs. As Fun Autopart mentioned previously, the combination either burns too soon, too late or fails altogether, causing starting failures even after getting gas.

A noticeable gasoline odor and dangerous exhaust fumes will come from the exhaust if the fuel is not completely burned. If left ignored, the engine would suffer.

Rough And/Or Loud Idle (With Vibration)

If your car’s spark plugs are poor, you also might notice a harsh or loud idle, and the vehicle may shake as a result. This occurs because your O2 sensors get thrown off by the residual gasoline from misfires introduced by defective spark plugs.

Consequently, they extract gasoline from the cylinders, creating an underfueling condition. When fuel economy is low, the engine suffers choppy idling and more engine failures. 

The engine’s RPM could also swing wildly at lower speeds. There’s a tachometer in the center console to demonstrate that, or you can just hear your motor out. Bad spark plug sound is usually a knock, a rattle, or a ping.

Higher octaves come from greater revs, while lower octaves come from reduced revs. When such an issue arises, your engine control unit (ECU) will attempt to rectify the situation by leaping, causing your car to shake when accelerating.

Rough And/Or Slow Acceleration

Particularly obvious is the reduced responsiveness of the gas foot under conditions where rapid acceleration is necessary. Misfires, which induce a lean fuel/air ratio, are the root of hesitancy during acceleration.

If your vehicle struggles or stalls when you hit the accelerator, you might need some replacement spark plugs.

Poor Fuel Economy

Not only is it ineffective, but it also wastes gasoline if the air/fuel ratio is off or the piston isn’t burning correctly. Since much gasoline is either escaping the car unburned or is being burned inefficiently, you would need more petrol to reach the same level of efficiency that the driver demands.

Keeping tabs on your car’s gas mileage is a great thing. Many factors can lead to poor gas mileage, but if it suddenly drops, it could be because your spark plugs are dirty or damaged.

Difficulty Starting Vehicle

Inadequate or worn-out spark plugs can make a car difficult to start or cause it to stall. When your automobile is at rest, it may experience the greatest trouble starting because it requires a great deal of power to counteract its inertia.

Since spark plugs rarely all break at once, a defective battery is more likely to be at fault if the car does not start at all. Try these dead car battery tricks in that case.

Check Engine Light

The spark plugs are one of the main contributors to the presence of the “check engine” light. 

This is because today’s vehicles are equipped with a wide variety of devices that can immediately begin relaying any issues they are experiencing to the PCM. The same holds true for the spark plugs; when they start to fail, the ECU will send out warning signals.

To be more specific, misfires are what bring on error codes. Expect a misfire in the cylinders due to faulty spark plugs, and the computer will report a P0300 or equivalent diagnosis.

Spark Plug Replacement Cost

If you need to replace your car’s spark plugs, ensure you get the same kind the car originally came with. Copper, single platinum, double platinum, silver, and iridium are just a few available varieties.

A few are costlier than others, but each has its own unique characteristics and traits that make it ideal for a specific set of automobiles. See the manual or get in touch with a trusted dealer to find out which is suitable for your car.

While many opt to replace only the faulty spark plugs (as indicated by the error messages thrown by the ECU or by visual inspection), others prefer to replace all the units in one go. Knowing exactly the number of plugs you need is essential when purchasing because they are sold singly.

The cost of a spark plug, on average, is under $10. Having spark plugs professionally fitted can charge anywhere from $50 to $200, but installing them on your own is simple and costs nothing. The spark plugs in most automobiles are conveniently located close to the engine.

If you’re going to do the work yourself, check the repair handbook for more tips, tricks, advice, and cautions.

Most spark plugs have a threaded base that fits into the head of an aluminum engine. Due to the delicate nature of aluminum, you can easily strip these spark plug threads if the heads get improperly tightened. This costly mistake will necessitate either re-tapping the hole or purchasing a new head.

Wrapping Up 

Knowing “What do bad spark plugs look like?” and the common symptoms of defective plugs help to take proper measures for your car’s health and performance. In the worst case, your vehicle might die completely, costing you a hefty repair. Thus, it’s always essential to have a once-in-a-while visual inspection and close-up examination!