Symptoms of Faulty Glow Plugs On Diesels

Glow plugs play an integral role in allowing your diesel engine to create combustion. Similar to a spark plug, glow plugs are responsible for assisting in igniting the air-fuel mixture needed to produce power, however, they also differ in some major ways from their gasoline engine counterparts.

Like other engine components, glow plugs will gradually experience wear over time and may eventually lack the ability to properly assist in combustion. In this article, we’ll go over what glow plugs are, the symptoms you may experience if yours are failing, and how to prevent premature glow plug failure in the future. 

What Is a Glow Plug

In gasoline engines, the spark plugs are responsible for producing the electrical spark used to ignite the air-fuel mixture within the combustion chamber, as gasoline is able to be ignited simply through an electrical arc. Diesel engines differ quite considerably, as diesel fuel is not able to be ignited from a spark, but instead requires the correct level of heat and pressure.

This is where the glow plugs come in. Rather than creating a spark for ignition, glow plugs instead are used to pre-heat the engine’s cylinders to the proper temperature needed for combustion.

While spark plugs are continually firing on each stroke of the engine, glow plugs are primarily used for initial start-up, particularly when the outside temperatures are low and the air-fuel mix may need some additional heat.

Symptoms of Faulty Glow Plugs

Hard Starting

If you turn your key in the morning and realize your engine is struggling to turn over, particularly on cold mornings, it may be due to faulty glow plugs that are not able to provide the necessary heat for initial combustion.

No Start

When glow plugs are unable to reach an adequate temperature, it may cause issues starting the vehicle, or prevent the engine from turning over at all. This issue will be most prevalent during particularly cold days, as the plugs are vital for maintaining 

Glow Plug Light/Check Engine Light

If you’re experiencing issues with your glow plugs, there’s a good chance they’ll be accompanied by either a blinking glow plug icon or a check-engine light on the dash, warning you that your plugs are not at the proper temperature. 

If you notice either of these two lights appear on your dash as you drive, it’s important to have your vehicle inspected by a trusted diesel repair facility as soon as possible, especially if you’re not certain the check-engine light is related to your glow plugs. 

Smoke From Exhaust on Start

If your vehicle manages to turn over but seems to struggle initially, accompanied by smoke from the tailpipe, it may be due to glow plugs that are nearing failure. They may still be able to get the vehicle started, but the initial rough idle from the lack of proper combustion may cause some dark smoke to emanate from your exhaust pipe. 

When Do I Need to Replace My Glow Plugs

If you are experiencing any of the above-mentioned issues, you should have your motor inspected for glow plug issues, as these are telltale signs your plugs are on their way out.

In general, glow plugs should be replaced between every 80,000-100,000 miles to ensure your vehicle is always able to start up without a problem. Some glow plugs that use materials like ceramic may last longer than less-expensive options.

Diesel Maintenance & Repair in Summerlin, Las Vegas

If you notice any of these symptoms, or believe your diesel’s plugs are nearing time for replacement, don’t hesitate to schedule with the experienced diesel technicians at Matson Point S in Summerlin, Las Vegas. Our team has the equipment and expertise needed to provide your diesel with the premier diesel maintenance and repair services in the Summerlin area!

Give us a call or schedule online today to secure your appointment with our friendly and knowledgeable team!