How to check glow plugs in a car? Damage and self-replacement

The correct operation of the engine depends on many factors. Glow plugs will certainly play a key role. Without them, the operation of the drive unit may be impaired. If you are the owner of a car that runs on diesel fuel, i.e. with a diesel engine, then you must be wondering how to check the glow plugs. When are you most likely to be deficient in these parts?

The main problem may be starting the engine head. Diesel users are well aware of how many problems can await them in the cold season. Such engines are much more sensitive than gasoline engines and will respond to lower temperatures in autumn and winter. In cold weather, a diesel unit may simply not surprise you. The reason may be that you did not replace the glow plugs in time. 

How to check glow plugs? methods

There are many different ways to check the status of these elements. Thanks to this, you will be able to know if they are in good condition or if they should be replaced. You can try to carry out such an operation yourself or immediately contact a familiar mechanic or an authorized repair service. 

It is possible that for various reasons you will not have access to a mechanic, and you will need a vehicle urgently. then a skill like checking glow plugs can definitely come in handy. Therefore, it is worth knowing not only what function glow plugs perform, but also how, for example, to unscrew them.

The role and work of glow plugs

Before you learn how to test glow plugs with a multimeter or otherwise, you must know how they work. These elements are installed in diesel engines and are categorically not combined with spark plugs that are used in gasoline cars. They are not the same because those used in diesels will not have the task of creating a spark to ignite the mixture. In diesel engines, the mixture of diesel fuel and air ignites due to the high pressure. 

Glow plugs are used to ensure proper heating of the combustion chamber. Thanks to this, the engine has an easier start at low temperatures. Please note that in the case of two-phase glow plugs, i.e. the older type, they turn off as soon as the engine is started. With further operation of the engine, they will no longer participate in it. 

Three phase glow plugs

Currently, the newer type of glow plugs is most commonly used, i.e. three-phase. They work a little differently. Their main advantage is that they warm up much faster. They need 2 to 4 seconds to do this. They are able to reach higher temperatures, which can reach up to 1300 degrees Celsius. Moreover, after starting the engine, they do not turn off. They will continue to perform their function, because thanks to them, the on-board computer will correct the conditions in the combustion chamber. This facilitates the formation of the exhaust gas mixture.

This process will continue until the vehicle has warmed up to operating temperature. This will ensure better combustion quality and lower harmful emissions. Therefore, it is an important process due to the diesel particulate filter. This prevents it from becoming clogged with unburned fuel residues. Spark plugs clean the filter by burning soot particles. It's good that you know how to replace glow plugs and how to check their condition.

How to check if the glow plugs need to be replaced?

How to check if the glow plugs are working should be an important question for any driver who cares about getting the job done right. diesel engine in his car. Fortunately, in practice, these elements rarely fail. 

In fact, this is a simple heater with fixed elements. You will not be able to unscrew them to look inside and check the condition from the inside. The error may simply be invisible. Moreover, at present, cars have modern diesel engines that will light up without problems at negative degrees outside. How do you know when it's time to check your spark plugs? 

Glow plug indicator light and other signs of a bad glow plug. When does it need to be replaced?

A symptom to look out for is problems with low temperature starting. In addition, you may notice that immediately after starting the engine, a distinct rough running of the engine is heard. This may mean a drop in engine power before it has even warmed up. The good news is that you don't have to worry about how to check your glow plugs. 

New cars won't require complicated troubleshooting, as a faulty glow plug will generate a computer error. You will notice a yellow light with a bulb that looks like a spiral. This is a very convenient solution that can save you a lot of time and nerves. This indicates that the glow plugs are faulty. Pay attention to only one caveat. This indicator may also indicate a malfunction in the injection system.

Checking Glow Plugs - Other Ways

In addition to control, there are other methods recommended by car mechanics. The initial step in checking the glow plugs is to check the power. This will allow you to check if the spark plug is receiving power. In any case, how to check glow plugs with a multimeter is described in many manuals, and this is not a difficult method. Thus, you only need to connect the negative end of the 12V tester to the negative terminal of the battery, and then touch the other end of the tester to one of the visible positive terminals of the spark plugs. 

The second person must turn on the ignition. At this point, the vial indicator should light up. The next step is to check the spark plug without removing it. It is enough to use a multimeter for this purpose, i.e. universal meter. It's always worth having one in your garage or car, which also comes in handy for other essential checks like checking your battery. Checking the glow plugs with a multimeter will also be very simple. You just need to set the resistance measurement on the device. 

Then you should touch one probe to the mass of the engine, and the other to the tip of the spark plug. If it turns out that the meter shows no resistance, then it is likely that it is damaged. You will perform a measurement that will confirm this diagnosis when you remove the spark plug. However, this is a dangerous occupation, you need to be very careful. Connect a piece of wire to the battery positive and to the glow plug terminal. Connect the other to the ground of the car and the part above the heater. A functioning candle will warm up in a few seconds, which you will immediately notice.

Glow plugs in diesel engines are responsible for heating the combustion chamber to the desired temperature. This allows the engine to be started even at very low temperatures. Candles are very simple devices. Newer cars allow you to view the operation of the spark plugs on the on-board computer, but you can also use a multimeter for this purpose. Taking care of the proper condition of the spark plugs will allow you to avoid an unpleasant surprise in the form of an inability to start the car on a winter morning.

Frequently Asked Questions

When should spark plugs be replaced?

Spark plugs can last up to 100-30 kilometers. However, for safety reasons, it is best to replace them in accordance with the manufacturer's recommendations, i.e. every 40-XNUMX thousand kilometers.

How to recognize damaged glow plugs?

Symptoms of damaged spark plugs can be trouble starting your car in cold weather. Another symptom to watch out for is erratic engine operation. If you notice these signals in your car, check your glow plugs. In new vehicles, when the glow plugs fail, a yellow indicator with a spiral bulb lights up on the instrument panel display.

Do glow plugs affect engine performance?

Glow plugs in a car affect the amount of fuel burned, proper combustion of the diesel particulate filter and the overall condition of the engine.