If you own a diesel car, there are a lot more things you need to think about when it comes to maintenance than if you own a gas-powered car. The glow plug is an important part that you should pay special attention to.
Most diesel engines need glow plugs because they provide the heat that is needed for fuel to burn in the cylinders of the engine. Some specialised engines use adiabatic heating instead of glow plugs to start the fuel, but this is not common in cars for the general public.
Read on to find out more about glow plugs and how important they are for diesel cars.
What Is a Glow Plug?
Everyone knows that diesel engines take a little more time to start up. This is because it needs a lot of heat to burn safely and effectively.
But different things can take away the heat needed to start a fire. Some of these things are cold weather and the fact that the cylinder block and cylinder head soak up heat. Here are where glow plugs come in.
They are parts that look like spark plugs and are very important for getting diesel engines going. They do this by giving the engine the heat it needs to start (750 to 850 degrees Celsius). When this happens, the glow tube will start to light up. This is how glow plugs got their name.
Glow plugs not only help diesel engines start, but they also keep them running and make sure they are working at their best.
Glow Plugs Vs. Spark Plugs
People often get spark plugs and glow plugs mixed up, but they are two different parts of a vehicle. In gasoline cars, spark plugs are used.
Since gasoline engines don’t need as much heat to start, spark plugs create the spark in the combustion chamber that starts the mixture of fuel and air burning.
Since a diesel engine needs more heat to compress the cylinders, the heat from a spark plug can’t help it start. This is why glow plugs are used instead in diesel engines.
Do All Diesel Engines Require a Glow Plug?
People often think that diesel engines and glow plugs go together and that you can’t have one without the other. Glow plugs are only used in diesel engines, but not all diesel engines need them.
Basically, diesel cars that use an electric starter need glow plugs. So, there are still a lot of diesel vehicle models on the market, especially for the military, that can run without glow plugs.
In this case, the heat needed for auto-ignition is made by the adiabatic compression of the fuel-air mixture.
Can You Start a Diesel When a Glow Plug Fails?
Even though glow plugs are very important for starting diesel engines, you can still start a modern car even if it doesn’t work. But this can’t happen if there are computerised rules about who can get on board.
If you didn’t have these rules, you might be able to start the car even if the engine was cold. When you try to start the car, the glow plug might not heat up all the way, but it will heat up just enough to start the engine. But you probably shouldn’t make it a habit to start your car this way.
If you try to start a diesel engine with a broken glow plug and fail, you might flood it. This happens when there is too much fuel in the cylinder, which makes it harder to start the engine.
Is It Possible to Roll Start a Diesel?
The battery is what gives the glow plugs their heat, so they can warm up the cylinder. If the battery is dead or completely drained, it is almost impossible to push start the car.
This is because the engine needs a lot of heat to start running.
Is it Bad to Cold Start a Diesel?
When starting a diesel engine in cold weather, you have to be more careful than when starting a gas engine. Gasoline is much easier to start a fire with than diesel because it is much more flammable and because some of it is a gas at room temperature.
Diesel is also hard to work with in cold weather because it starts to gel at temperatures below 40°F. So, it’s harder to start the car because the engines need to spray fuel into the air to start.
With glow plugs and other modern technologies, it’s much easier to start a diesel engine from cold than it was with older models.
Causes of Glow Plug Failure
Since glow plugs add the extra heat that is needed for the combustion chamber to light, it is hard to start a diesel car when they start to fail. If the weather is good, you may be able to get the fire going after a few tries.
But when it’s cold, a broken glow plug isn’t likely to get the engine to start. So, if you start having trouble starting your diesel car, you should have your glow plugs checked.
Glow plugs can fail for a number of reasons, but the most common ones are high voltages reaching the plug and too much heat.
Other reasons why glow plugs fail are:
If you don’t use the right glow plugs for your engine,
Long power supply because a relay got stuck.
Because of injector drip, the glow plugs wore down.
If all of the glow plugs stop working at the same time, it’s not because of normal wear and tear. So, you need to figure out the exact cause to make sure it doesn’t keep happening.
Signs of Glow Plug Failure
If your glow plugs start to fail, you need to get new ones right away. If you don’t, you might not be able to start the car and be stuck somewhere. Other signs of bad glow plugs, besides the check engine light on your dashboard, are:
#1 Difficulty Starting the Engine
Most of the time, the engine won’t start when the glow plugs are bad. Because they are broken or because of something else, glow plugs can’t get hot enough to light the combustion chamber. Even more so when it’s cold outside. Check the glow plugs if there are no problems with the fuel or the battery
#2 Rough Idling
In addition to having trouble starting the engine, a rough idle is a subtle sign that the glow plugs are broken. When this happens, you’ll see white smoke coming out of the exhaust for a few minutes before the engine starts.
#3 Engine Misfiring
For a diesel engine to burn, it needs to have a high compression rate and the fuel must be injected at the right time and in the right amount. Misfiring can be caused by problems with the fuel, the injection, and the compression.
The glow plugs and compression pressure heat up the combustion chamber when the engine is turned on. If the glow plugs are broken, the engine won’t get the heat it needs to burn fuel, so it will misfire.
#4 Increasing Fuel Consumption
Most of the time, the quality of the fuel and the temperature are what determine how well it burns, but the performance of the glow plugs may also have an effect.
During the winter, diesel may be mixed with other things to make it less likely to freeze. When this happens, the fuel will be less efficient because it has less energy. So, you should change the engine’s operating temperature to make sure it burns all of it, which will increase your mileage.
If your glow plugs are broken, it will be hard to get the engine to the right temperature for combustion. This then affects how well the engine works, which makes it use even more gas.
Some of the other signs that glow plugs are failing are:
Loss of power in general
slowed things down
How often Should You Replace Glow Plugs?
Glow plug failure is one of the biggest worries for people who drive diesel vehicles. They are cheap to replace and last a long time, which is good. Glow plugs should last up to 100,000 miles before they stop working because of normal wear and tear.
But that isn’t always the case, and you should always be on the lookout for a failed glow plug. The longer you wait to get new ones, the harder it will be.
For example, if your car has an engine with four cylinders, it will be hard to start with one broken glow plug. If two or three are broken, it’s almost impossible to start.
Always Carry a Spare Set of Glow Plugs
Since there are many things that can go wrong with glow plugs, they might not all break at once like they would if they were just worn out. So, you risk not being able to start your car all of a sudden.
If self-service is needed, it is important to have a spare set of glow plugs.