Glow plugs are like mini heaters in your car?s bonnet. As heating elements, they warm the air and diesel in your engine for effective combustion.
Glow plugs share the same functionality as spark plugs. But rather than sparking the ignition in petrol engines, they heat air and fuel to start diesel engines.
Each diesel engine has a glow plug for every cylinder, which is why different makes and models need different numbers of plugs.
Glow Plug Anatomy
A glow plug begins as a heating coil, which is inserted into a metal tube. The tube is filled with electrically insulating ceramic powder and sealed at one end. When the glow plug is electrically energised, its heated tip can exceed 1000C within a few seconds.
Ceramic glow plugs are an alternative to standard plugs. These include a heating element that is encased in ceramic (Silicon Nitride). The casing allows the glow plugs to heat particularly quickly, reaching higher operating temperatures for extended periods of time.
Note: good-condition, high-quality glow plugs heavily reduce exhaust gases emitted by your vehicle, keeping your environmental impact to a minimum.
How Do Glow Plugs Work?
Unlike spark plugs, glow plugs need to be warm enough under pressure to self combust. In hot weather, fuel needs little assistance from other car parts to achieve this. However, diesel engines often struggle to ignite fuel in cold weather. The glow plugs heat the fuel in order for the engine to start.
To start the engine, the intake air is compressed and, as the piston rises, the engine injects diesel into the combustion chamber. The injected fuel combines with the air, evaporates and ignites.
The ignition happens so quickly after evaporation that these processes are almost simultaneous.
Glow plugs undergo a three-phase process when the engine is started.
1) Pre-Heating: the glow plugs heat quickly to start the engine.
2) Temperature Maintenance: the glow plugs maintain their temperature to ensure optimal combustion.
3) Post-Heating: the glow plugs remain heated for a few minutes after the engine has been started to maintain the combustion process.
Read our blog post on how glow plugs are manufactured here.
Finding the Right Glow Plugs
With thousands of glow plugs available to choose from, it can be an overwhelming task to find the replacements for your car.
But by entering your number plate into our car lookup tool, you can find the best glow plugs for your vehicle within seconds.
With one of the widest high-quality glow plug ranges on the market, DIY Car Service Parts stocks plugs from the top-recommended manufacturers, providing glow plugs for every make and model.
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