Signs Your Diesel Engine’s Glow Plugs Are Going Bad

Diesel engines use glow plugs instead of spark plugs to aid in combustion. Diesel engines must reach a certain temperature before they will fire up, and the glow plugs heat up the combustion chamber to make it hot enough for the engine to start and run. Glow plugs last on average about 100,000 miles. Checkpoint Motors warns that if you drive a high-mileage vehicle, your glow plugs may be going bad. Here are signs that they are.

Difficult Starts

One of the first things you will notice if your glow plugs are going bad is that it is difficult to get your engine started. This is especially true if it is cold outside. As we mentioned, the combustion chamber must get to a certain temperature in order for the air and diesel fuel inside of it to ignite. If the glow plugs are not warming up the chamber the way they need to, you may not be able to get your diesel automobile started.

Misfiring Engine

This temperature is 450 degrees Fahrenheit. Diesel engines get much hotter than gasoline engines do. If the combustion chamber is not at 450 degrees, your engine will misfire even if you are able to get it started. This is because the heat inside of the engine has not reached the desired temperature for the air and fuel inside the combustion chamber to fire up properly.

Rough Idling

The cool engine temperature from the faulty glow plugs will also cause your vehicle to idle roughly. Again, if the air and diesel fuel are struggling to fire, this will directly affect your engine’s performance. Consequently, you will feel the engine idle roughly because it is trying to prevent itself from stalling. This will be the case until you replace the faulty glow plugs.

Poor Diesel Fuel Economy

When your engine is struggling to run, you will notice a reduction in your fuel economy. This is because the engine is burning through the diesel fuel more quickly and its efforts to prevent stalling. Unfortunately, if the glow plugs are unable to warm the engine to the desired temperature, you will continue to experience poor fuel economy until they are replaced.

White Exhaust Smoke

Finally, when the engine is running colder than it needs to be, you will notice white exhaust smoke pouring out of the tailpipe, especially when you first fire up your diesel engine. You may notice that this smoke has a particularly pungent fuel odor to it. This is because the combustion chamber is not hot enough to burn away all of the diesel fuel that is in it. In rare cases, the faulty glow plugs may also cause black exhaust if the air and fuel mixture in the combustion chamber is off.

Checkpoint Motors in Oregon City, OR, can help. We work on diesel and gasoline automobiles of all makes and models. Give us a call today if you think your glow plugs need to be replaced.

Photo by algre from Getty Images via Canva Pro

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