5 Signs That a Diesel Glow Plug Is Faulty

 The glow plugs make sure that even in cold weather, your diesel engine starts easily. How to identify damaged diesel glow plugs.

You might not be familiar with the glow plug unless you drive a diesel vehicle. It replaces the spark plug and is in charge of warming the cylinders of a diesel engine. They are a crucial component and frequently endure a long time, although they can become faulty with repeated use. We go over the primary indicators of a bad diesel glow plug.

Check MOT history online to see if broken glow plugs were the cause of a prior MOT emissions test failure.

The position and purpose of the diesel glow plug are also covered in this post. Let's start by quickly going over the warning flags.

The most typical sign of a bad diesel glow plug is trouble starting the car when it is cold. A misfiring engine and poor acceleration are some potential symptoms. These signs frequently appear along with a check engine light on your dashboard. To prevent failing the emissions test, check the MOT status and have a qualified mechanicrepair or replace the faulty glow plug(s).

The following is a more thorough list of the most typical signs of a damaged diesel glow plug:

1.      Vehicle Starting Issues - It could be challenging to start your diesel engine if the glow plugs are damaged. Insufficient heat is produced by the defective plugs to warm the cylinders. It can take several tries to start the motor if the plugs don't generate enough heat rapidly. Additionally, you might not be able to start the engine at all if the glow plugs are almost dead and the temperatures are very low. To determine whether a prior MOT test failure was brought on by this, perform an online MOT history check.

2.      The Check Engine Light or Glow Plug Light - These can come on when the glow plugs start to malfunction. With your OBDII diagnostic tool, you should scan the system to obtain the error codes. The P0380 "Glow Plug/Heater Circuit A Malfunction" error code may occasionally appear. It may also result in the P0670, P0671, P0672, P0673, P0674, P0675, P0676, P0677, P0678, P0679, P0680, P0681, P0682, P0683, and P0684, as well as the P0381, P0382, P0383, and P0384 errors. Engine management light illumination is a frequent cause of a MOT test failure on a MOT history checker.

3.      Poor Acceleration - In some cases, especially in colder weather, the engine's performance can be impacted by malfunctioning glow plugs. Replace the glow plugs if nothing happens when you press the accelerator pedal all the way down. However, numerous faulty parts frequently exhibit poor acceleration. Before drawing the conclusion that the glow plugs were at fault, you would need to conduct a more thorough investigation.

4.      Engine Misfiring - A misfiring engine happens when the fuel in the cylinder doesn't ignite properly. Any misfire is alarming, but when one is brought on by a defective glow plug, it can be quickly fixed. In order to properly warm up the cylinder and ignite the fuel, the glow plug is required. Although there are other problems that might lead to misfiring, a bad glow plug is an excellent place to start.

5.      Black Exhaust Smoke - This indicates a problem if your diesel car is spewing out black or dark grey smoke from the exhaust. These hues indicate that there is a problem with the combustion system. Black smoke, though, might also come from the diesel engine for other causes. If smoke is pouring from the exhaust and you are also observing other signs from our list, you should check the glow plugs.

Where Is the Diesel Glow Plug?

The cylinder head of the engine houses the diesel glow plugs. They are separately screwed onto each cylinder. The battery supplies 12 volts to power each glow plug.

They will have a wire carrying power attached to the top that will jut out, making them easy to spot. To access the glow plugs, you might occasionally need to remove the valve cover.

A Diesel Glow Plug's Purpose

Warming the cylinders allows the engine to ignite the fuel, and this is done by the diesel glow plug. The glow plugs aid in maintaining the engine's proper operation. Heat can be effectively drawn into the diesel engine because of the position of the glow plugs.

The glow plug is hardly ever necessary when the weather is perfect. To heat the cylinder sufficiently for combustion, however, the glow plug must be in top shape when temperatures drop.

Spark plugs versus diesel glow plugs

Despite having certain variances, glow plugs and spark plugs are fairly similar in nature. Here are a handful of the differences you'll see between the two:

1.      Fuel Type - First, diesel engines have glow plugs inserted, whilst petrol engines have spark plugs. Spark plugs are required for petrol engines in order to generate the spark that ignites the fuel and air inside the combustion chamber. Diesel engines, however, don't operate in this manner. The combustion process in a diesel engine simply requires heat, which the glow plug increases. It does not require a spark.

2.      Heat - Fuel is flammable and is sensitive to heat. A little spark is all that is needed to start combustion. But for diesel fuel to burn, there must be both compression and heat. The glow plug is used to provide the intense heat that is necessary for combustion to occur inside the cylinders. Intense heat produced by glow plugs aids in igniting the fuel/air mixture inside the combustion chamber.

3.      Durability - The glow plug will endure much longer than the majority of spark plugs. Only the cylinders are warmed using glow plugs before to ignition. After that, their use is minimal. The spark plug, on the other hand, keeps the engine running continuously. Cheap spark plugs may barely last 30,000 miles in total.

4.      Difference in Ignition - A spark is produced by the spark plug using electrical energy. The air and fuel mixture in the combustion chamber were ignited by this spark. There is no spark used in diesel glow plugs. They convert electricity into heat, which aids in lighting the mixture of fuel and air.