The great thing about diesel fuel is that it ignites on its own. This happens after it is put under pressure and then exposed to air. The only problem is that cold temperatures in the vehicle’s surrounding environment could make it more difficult for this ignition to occur. For this reason, diesel engines need glow plugs to assist in the ignition process.
Diesel glow plugs will basically warm up the engine’s cylinder before the fuel is ignited. This will make it easier for the fuel to be ignited in the cylinder. Do not confuse glow plugs with spark plugs because they are two different things. Spark plugs in a regular gasoline engine are responsible for creating an electrical spark which ignites the air and fuel mixture. The glow plugs are just warming up the cylinder so that the fuel will have an easier time igniting on its own.
A glow plug features an electrode that generates heat when it is activated. This will cause the plug to glow, which is why it is named that. This is similar to how an incandescent light bulb will glow after it heats up too. This glowing effect is what heats the cylinder and allows for the successful ignition of the diesel fuel.
You will know when you have bad glow plugs because it will take up to 5 seconds for the diesel engine to start. Once that happens, the engine performance will be very weak. It will run rough for a little while because it will take longer for it to get to the right operating temperature. That is what happens when there is a misfire in one of the cylinders. At this point, the Check Engine light is going to illuminate on the dashboard and you may even see exhaust smoke coming out from the tailpipe. If the glow plugs are completely ruined, then your engine will not start up at all.
The typical replacement cost for a diesel glow plug will be anywhere from $100 to $350. The cost of the parts will be around $60 to $150 while the cost of the labor will be about $40 to $180. The exact cost will depend on the make and model of your diesel vehicle. There will also be added taxes and other fees as well. In general, it is not a very expensive part to replace. If you can find a reasonably priced mechanic with a low hourly rate, then it will reduce your expense even more.