Spark Plug Failure Cause

The #1 Cause of Spark Plug Failure

Many factors can cause a spark plug to fail; from incorrect heat ranges to improper gapping, to chemical contamination.

Sponsored by NGK Spark Plugs

Many factors can cause a spark plug to fail; from incorrect heat ranges to improper gapping, to chemical contamination. Yet 90% of spark plug damage claims are due to improper torque. Proper installation torque is critical in the plug’s ability to dissipate heat out of the combustion chamber and into the cylinder head. Not using a torque wrench when installing plugs can lead to over-torquing or under-torquing a spark plug, which will cause damage to the plug and possibly the engine.

It’s critical to follow the manufacture’s torque specifications when installing a plug. Make sure to use a torque wrench that corresponds to the torque specified on the packaging of the spark plug. Specifications vary by seat type, thread diameter and cylinder head types; so make sure to account for these three factors when installing a plug. The difference between an over-torqued or under-torqued spark plug, is often using an incorrect tool or not using one at all.

Engine Damage from Insufficient Torque

An under-torqued spark plug will not make full contact with the cylinder head. This reduces a plug’s ability to transfer heat and will result in elevated combustion chamber temperatures. Such temperatures can cause pre-ignition and detonation and lead to engine damage. Excess vibration and subsequent damage to the ground electrode and terminal nut may also occur. An over-torqued spark plug can cause stress to the metal shell, leading to thread damage or breakage. Over tightening can also compromise a plug’s internal gas seal or even cause a hairline fracture in the insulator. Such damage results in problems similar to an under-torqued plug: improper heat dissipation or exhaust gas blow-by.

Thread Damage from Excessive Torque

In addition to using the correct torque wrench, take care to clean the area around the spark plug hole with compressed air and make sure the plug thread is free of lubricant and carbon build-up. Torquing against debris and build-up around and on a spark plug prevents the plug from making full contact with the cylinder head, even if a torque wrench indicates otherwise. Secondly, avoid using chemicals during installation. Refer to the manufacturer’s recommendations on use of anti-seize, as it’s not recommended for all plugs and may cause thread shell damage. Lastly, make sure the engine is cool before installing or removing a plug to avoid damaging to the cylinder head.

Remember anything interfering with the torque process can cause a plug to fail or worse, engine damage.

For more information or questions about installing spark plugs you can reach out to the NGK Technical Support line by calling 877-473-6767 or visit them on the web at www.ngksparkplugs.com.

You May Also Like

Beam vs. Conventional Wiper Blades: Which is Better?

As you’re aware, all car parts change over time. This includes wiper blades, which some vehicle owners might not consider to be a crucial part. As with any other vehicle component, research and technology have improved the way wipers are designed, how they’re installed, and their overall function.  Weather and road conditions vary and will

As you’re aware, all car parts change over time. This includes wiper blades, which some vehicle owners might not consider to be a crucial part. As with any other vehicle component, research and technology have improved the way wipers are designed, how they’re installed, and their overall function. 

6 Signs It’s Time to Put Down the Pen and Ditch the Paper 

There’s no time to hesitate.  The surge in the aftermarket sweet spot — or vehicles in the six- to 12-year age range that will soon require significant repairs — reached 94 million in the first half of 2021, according to Experian Automotive. That total accounts for nearly 31% of all vehicles in operation.  That percentage

Trust in Delphi Technologies, the OE for your ignition coils

Delphi Technologies is the only OE manufacturer that has a full-line ignition coil offering. Delphi Technologies’ ignition coil program covers 97% of European, Asian and Domestic applications with 392 SKUs, and serves as the OE on over 51 million applications. This ranges from a variety of vehicle manufacturers such as BMW, Buick, Cadillac, Chevrolet, Dodge,

Engineering behind chassis: high and low-friction parts 

When it comes to chassis parts, simplicity is the key to success. Overengineering components can not only make it more difficult to perform repairs, but it some cases may cause earlier repairs/failures in certain scenarios. What is overengineering? Overengineering is often described as designing a product or solution in an unnecessarily complicated way where a

What Is The Cost Of A Wheel Bearing Comeback?

Every time your shop works on a vehicle, there is a potential for a comeback. The cause of the comeback could be due to technician error, miscommunication or additional failures on the vehicle. The random nature of these comebacks can make them difficult to anticipate. But, comebacks and financial losses due to low-quality or defective

Other Posts

Training Techniques to Teach Today’s Techs

The need, dependency and resources for training continue to grow. This video is sponsored by The Group Training Academy.

Learn To Advise Customers, Not Just Sell Them

Service advisors are a liaison between the tech and the customer. This video is sponsored by The Group Training Academy.

Quality-Built Brake Pads and Rotors Powered by MPA

Backed by over fifty years of product innovation and engineering expertise, Motorcar Parts of America is proud to announce the addition of Quality-Built replacement brake pads and rotors to our extensive product portfolio. This full line of brake system components provides a wide range of application coverage and options for every type of driver and

REPLACEMENT TIME: CV AXLES 101

When it comes to your vehicle, there are many different components to be aware of. From whining to clunking to screeching, failing components can make noises, this could be a sign letting you know the CV axles need to be replaced. A common replacement part in front-wheel drive vehicles is the CV axle. CV Axles