Signs Your Glow Plug Needs to Be Replaced

Nothing sounds as good as the steady hum of an engine at work. When you turn the ignition to your car, you expect the engine to fire and the vehicle to run.

In contrast, nothing causes frustration like that moment when you need to go somewhere, and your engine just won’t start. It’s equally frustrating when your diesel engine starts but refuses to continue to run. 

You may need a new glow plug. The glow plugs in a diesel engine are the heartbeat of the vehicle. They make the engine run smoothly and consistently, and they give you confidence that your vehicle will get you where you want to go. 

Keep reading to learn everything you need to know about glow plugs and why they’re an essential part of your diesel engine. 

Driving With a Bad Glow Plug

You can drive with a bad glow plug if you have to. But the drive should be short and should take you to the mechanic’s shop. 

Driving on a faulty glow plug will result in continued poor performance. Eventually, your engine will misfire. Misfiring in turn lowers your fuel efficiency. 

You’ll find yourself needing more fuel for fewer miles on your engine. The faulty glow plug will prevent your engine’s combustion chamber from getting the heat it needs to make the engine work. Replacing the glow plug will give you a diesel engine that starts and runs efficiently. 

Signs Of a Bad Glow Plug

So how do you know if your glow plugs are going bad? When you take your vehicle in for regular diesel engine maintenance, a technician can quickly spot a bad glow plug. But there are telltale signs you can spot on your own if you know what to look for. 

Difficulty Starting

Vehicles and engines in general struggle to start in extremely cold weather. 

Glow plugs help a vehicle start, especially in cold conditions. Thus, if you have a hard time starting your diesel engine in the cold, you may have a problem with a glow plug. You also could have issues with your vehicle’s fuel or battery. 

Glow plugs help heat the vehicle’s combustion chamber. If the combustion chamber is cold, it will struggle to ignite fuel. This in turn causes the engine to not start. 

When your vehicle just won’t turn over, check your glow plug. 

Misfiring Engine

A misfiring engine is the most common sign of a bad glow plug. When your glow plug isn’t working properly, the fuel will not ignite in the cylinder, and your engine will misfire. 

Glow plugs heat the incoming fuel. To combust, you need a high compression rate in a diesel engine and adequately heated fuel. The combustion chamber itself should be around 450 degrees F. 

If your glow plug isn’t doing its job, the fuel will not be hot enough, and fuel injection will fail. As a result, your engine will misfire. 

More Fuel Requirement

When your glow plug isn’t working properly and your engine is misfiring, your vehicle will require more fuel for fewer miles. In short, you’ll have poor fuel efficiency. Malfunctioning glow plugs will not adequately heat fuel. 

Low temperatures mean the engine cannot do its job well. It chugs along instead of purring, and you find yourself at the fuel pump more often than you used to. 

Dark Smoke

If your vehicle has begun to emit dark smoke from the exhaust, you could have a problem with your glow plug. An air-fuel ratio imbalance will lead to this dark smoke. You may either have an excessive amount of fuel or an insufficient amount of oxygen. 

Glow plugs affect your diesel combustion. When your glow plug isn’t working properly, your diesel engine will not combust properly. Dark smoke will roll from your pipe. 

Weak Acceleration

A faulty glow plug can cause your vehicle to accelerate poorly. When you press on the gas and the speed just isn’t coming quick enough, have your glow plugs checked. 

When your glow plugs aren’t adequately heating fuel, the engine won’t work efficiently. This means the cylinders don’t fire efficiently, and your vehicle just won’t accelerate quickly. 

Of more concern, if you have a faulty glow plug, the engine may just stop running altogether. It will start and then stop. Have your glow plugs checked if you notice these symptoms. 

White Smoke

In cold weather, white smoke will commonly come from your vehicle’s exhaust. However, if the white smoke continues even after the temperatures rise, it’s time to have your glow plugs checked. 

When your fuel system has a combination of low compression and not enough air, white smoke results. A bad glow plug control module will cause such a problem. 

Check Engine Light

When your glow plugs go back, your engine light may light up. This light indicates you have a serious problem with your engine, and you need to find a mechanic as quickly as you can. 

The check engine light could indicate problems other than your glow plug. Regardless, do not ignore this light. It means your engine needs help right away, and failure to seek this help could result in much bigger problems down the road. 

What Happens When You Replace Glow Plugs

When you replace your glow plugs, you will see a remarkable difference in your engine’s performance. You might not even know your car was performing that poorly until you begin driving with the new glow plugs. 

With functioning glow plugs, your car’s combustion chamber functions at the right temperature. The engine will fire as it should, and you can accelerate with ease and confidence. Best of all, your car will start every time you turn the ignition, and the engine will stay running. 

Maintain Your Diesel Engine

To ensure that your glow plug is functioning properly, keep a regular maintenance schedule. Take your vehicle in for a tune-up with a qualified diesel mechanic regularly so you can avoid the little problems that can cause bigger problems. If you’ve noticed any signs that your glow plug is going bad, seek out a qualified mechanic today. 

Are you looking for an expert in diesel engines? If so, contact us. Our certified mechanics offer a full range of diesel engine care from the basics of an oil change all the way up to intricate engine repair. 

Give us a call today, and let us help you. 

How Long Do Brakes Last on a Truck?

How Long Do Brakes Last on a Truck?

Nothing will cause your heart to stop like the moment your truck won't stop. When your truck brakes fail you, chaos can ensue. You're driving a heavy vehicle, possibly with a heavy load, and your momentum is significant.  A truck with failed brakes can cause all...

Troubleshooting Your Diesel Engine

Troubleshooting Your Diesel Engine

Do you own a diesel truck? There's no denying the importance of regular maintenance to keep it running properly. That's because you work hard and rely on your truck to hold up day after day on the job and on the road. When you experience mechanical issues with your...

How Often Should You Do Diesel Engine Maintenance?

How Often Should You Do Diesel Engine Maintenance?

Did you know that diesel fuel contains approximately 10% to 15% more energy than gasoline? This means that vehicles with a diesel engine can travel about 20% to 35% farther on one gallon of fuel. However, to get the most out of your engine, you have to keep up with...

How to Maximize Diesel Engine Efficiency

How to Maximize Diesel Engine Efficiency

Did you know that 70% of U.S. freight is transported by Class 8 trucks? Whether you're transporting oil, food, or another commodity, you need to increase your diesel engine efficiency as much as possible.  Especially now, with diesel prices on the rise, truckers...

Diesel vs Gas: What Makes Diesel Better Than Gas?

Diesel vs Gas: What Makes Diesel Better Than Gas?

Since 1897, when Rudolf Diesel invented the four-stroke combustion engine, we've used diesel in our trucks to transport goods across the country. Our biggest and most powerful vehicles run on diesel, and that's a testament to the capability engine it runs on. The...