Because diesel has a relatively low ignition temperature and intake air temperature, it is easy to start a warm diesel engine without the need of a glow plug or in warm climes. This, however, is not enough to guarantee that the injected fuel ignites properly in all temperatures, which increases exhaust emissions.
This is resolved with a glow plug. Every diesel engine cylinder has an electrical heating component that makes sure the engine starts every time, regardless of the weather. Well, in this reading, I will be explaining what a glow plug is, its functions, its diagram, its types, and how it works. I’ll also be exploring the symptoms and replacement cost of a glow plug.
Let’s Get Started!
Contents
What is a Glow Plug?
A glow plug is a type of heating element used in diesel engines to promote effective fuel combustion by heating incoming fuel and air. Your engine is started by the burning of gasoline, enabling you to drive. There is one glow plug in each cylinder of your engine, either in the combustion chamber (for direct-injection engines) or the pre-chamber (for pre-chambered engines).
By preheating the air in the combustion chamber and accelerating the engine’s temperature to its ignition point, glow plugs make starting a diesel engine in cold weather easy. When you switch on the ignition, glow plugs activate automatically and usually last for a few seconds. Modern glow plugs are often driven by electricity and constructed of metal or ceramic materials.
Function of a Glow Plug in Diesel Engines
A glow plug is a type of heating element used in diesel engines to promote effective fuel combustion by heating incoming fuel and air. Your engine is started by the burning of fuel, enabling you to drive. There is one glow plug in each cylinder of your engine, either in the combustion chamber (for direct-injection engines) or the pre-chamber (for pre-chambered engines).
As a result, by preheating the air in the combustion chamber and accelerating the engine’s temperature to its ignition point, glow plugs make starting a diesel engine in cold weather easier.
Design & Diagram of a Glow Plug
Despite the fact that glow plugs come in different styles, they typically have a similar construction. They often have a hexagon-shaped head and a thin, threaded center unit that make it simple to install and remove with a wrench. A tight fit into the cylinder head is ensured by this thread.
At one end of the glow plug is the heating element, which contains a heating coil. It’s the component that warms up the air-fuel combination to aid in engine starting. The electrical connector is on the glow plug’s opposite end. The electricity required for the heating element to operate is supplied through this connection.
Types of Glow Plug
The most common types of glow plug are pressure sensor glow plug, ceramic glow plug and high-tech steel glow plug.
Pressure Sensors Glow Plug (PSG): These types of glow plug’s performance is optimized by the sensor and electronics in the PSG pin, which also greatly reduces particle emissions. The modern PSG operates by using its built-in sensor to measure the pressure within the combustion chamber and then sending the information to the engine management electronics so they can calculate the proper heating pattern for the glow plug.
Ceramic Glow Plugs (CGP): built for high temperatures, can reach temperatures of up to 1500°C in less than three seconds. Engines start more faster because to this quick heating. When used in low-compression diesel engines that comply with EPA regulations, it is advantageous.
High-Tech Steel Glow Plug: are of two varieties: GE and GN. Modern three-phase glow plugs, known as GN plugs, heat up rapidly, hold their heat while being ignited, then cool down in three minutes. The plugs resemble a long pencil. Modern high-tech steel plugs heat up in seven seconds, compared to the thirty seconds or more that older diesel engines need to heat up when using GE-type plugs. Generally speaking, GE plugs are smaller and resemble spark plugs more in size.
How Does A Glow Plug Works?
A glow plug is simply required for ignition, as opposed to a spark plug that operates constantly as you drive. The glow plug gets its name from the fact that it heats up and generates visible light when the heating element is electrified.
Before the fuel injector spray directs fuel onto the glow plug’s heated tip during fuel injection, intake air is compressed. Even when the engine is cold, the injected fuel combines with the compressed air, evaporates, and almost immediately begins to burn.
There are two varieties of glow plugs available. One that fits inside the cylinder and the other that fits within the manifold. Each cylinder contains a plug for glow plugs that are in-cylinder kinds. With the in-manifold type, each cylinder is supplied by a single glow plug. Hence, a diesel engine’s glow plug count will depend on how many cylinders it has, or it may have just one Thermostart (in-manifold) glow plug.
Eight plugs, for instance, would be used in an eight-cylinder engine using in-cylinder plugs.
Symptoms of a Bad Glow Plug
The noticeable symptoms of a bad glow plug include hard starting, engine misfiring, rough idling, decreased fuel efficiency, and what or black smoke from the exhaust.
1. White or Black Exhaust Smoke
Pouring white and black smoke from the exhaust is not a good indication. When there is insufficient heat in the engine to effectively ignite the fuel, white smoke is produced. The unburned fuel particles then smell like diesel fuel when they leave the engine through the exhaust.
The air and fuel mix being wrong, usually with too much gasoline, is what causes black smoke. All of these problems are exacerbated by glow plug problems.
2. Rough Idling
When the engine eventually starts, it will idle roughly and emit white smoke from the exhaust for several minutes. This is a sign that one or more glow plugs have burnt out, become carbon fouled, or are broken. Inspect the timing of the fuel injection if all of the glow plugs are burnt at the tips.
3. Difficult to Start
Most often, a difficulty starting an engine is a sign of broken glow plugs. Without properly functioning glow plugs, the combustion chamber could not warm up sufficiently in cold weather to ignite the fuel and start the engine.
Glow plugs should be examined whether the fuel or batteries are in good working order.
4. Engine Misfiring
High compression ratios and precisely timed and controlled fuel injections are necessary for the combustion process in diesel engines. This causes the diesel fuel to ignite and burn. Problems with fuel quality, compression, and fuel injection can result in misfires.
Compression pressure and glow plug heat are the sources of the combustion chamber’s heat. For ignition to occur, it must achieve a minimum temperature of 450°F, or 232°C. The engine chamber won’t get hot enough if the glow plugs aren’t working properly.
5. Bad Fuel Efficiency
Glow plugs aren’t usually the main element affecting fuel economy; there are other aspects to consider as well. However, glow plugs could be the cause if you’re experiencing some of these other symptoms and your fuel economy is significantly lower than normal.
How Much Does it Cost to Replace a Glow Plug?
A glow plug replacement typically costs between $242 and $296. Parts range in price from $100 to $117, and labor expenses are projected to be between $142 and $180. This range does not account for your particular area or for taxes and fees.
What is the lifespan of glow plugs? 80,000 to 100,000 miles is the typical lifespan of a glow plug, however this might vary depending of the brand, quality, and driving habits. You may be sure that your new glow plugs will be reliable for a while if you’re wondering how long they will last.
FAQs
Should I drive if my glow plugs are broken?
No, using a malfunctioning glow plug while driving is not safe. Your engine may misfire or run rough due to insufficient fuel ignition caused by an incorrect combustion chamber temperature. If you are traveling in unsafe conditions or at high speeds, this might potentially put you in danger.
Is replacing glow plugs a difficult task?
Even though cars have gotten more complicated over time, you can usually still change your car’s glow plugs on their own. Make sure you have the appropriate glow plugs for your car and a manual torque wrench before starting the task, though.What does a glow plug do?
A glow plug is a type of heating element used in diesel engines to encourage effective fuel combustion by heating incoming fuel and air. Your engine is started by the burning of fuel, enabling you to drive.
What happens if a glow plug malfunctions?
When the engine eventually starts, it will idle rough and emit white smoke from the exhaust for many minutes. This is a sign that one or more glow plugs have burnt out, been carbon fouled, or are broken.
A diesel without glow plugs—will it start?
No, on a chilly day, the diesel engine needs glow plugs to provide the first bit of heat in order to start. They serve no other purpose than this. If it’s warm outdoors, they will start without them as well. This is a condition indicator for diesel engines.
That is all for this article, where i explore what a glow plug is, it functions, diagram, types, and how it works. I also explained the symptoms of a bad glow plug and how much it will cost you to replace them. I hope it was helpful, if so, kindly share with others. Thanks for reading, see you around!