The spark plug is one of the most important parts in an engine. When a discharge passes through it, a spark appears, which ignites the fuel-air mixture. Improper operation can cause deposits to appear, and the color of the spark plug will indicate their origin.
deposits on spark plugs
...about changing the color of the spark plug
A common problem is a white coating on the spark plugs, which is caused by incorrect selection of spare parts, poor fuel mixture, air leaks, etc.
How to assess the condition of spark plugs
The condition of the spark plugs can be assessed by the nature of the internal combustion engine (ICE) and appearance. Irregularities in the ignition system may have the following symptoms:
- starting complication;
- missing spark;
- power drop;
- unstable operation, engine tripping;
- high fuel mixture consumption.
These symptoms may also indicate breakdowns in other parts of the engine, which provoke the appearance of carbon deposits, despite correct adjustment and the use of high-quality gasoline.
How to diagnose spark plugs:
- Read the vehicle's operating instructions and find out where the electrodes that supply the spark are located. Depending on the type of motor, they can be installed on the top or side. In engines with a hemispherical combustion chamber, 2 spark plugs are installed for each cylinder, in other types of internal combustion engines - one each.
- Prepare a socket wrench with a head suitable for the electrode size (16 mm or 21 mm).
- Clean the working surface with a rag and alcohol to prevent dirt from entering the cylinder.
- Disconnect the cable that is connected to the ignition electrode by pulling the rubber or plastic cap. There is no need to pull the wire itself: this can damage the connection.
- Unscrew the spark plug counterclockwise with a socket wrench. Pay attention to its color, the presence of an oil film on the electrode and thread, traces of erosion (destruction), etc. The part can be removed after the motor has completely cooled.
assessing the condition of spark plugs
Electrode sparking can be assessed using a multitester or a special stand.
The performance of candles is influenced by the following factors:
- fuel quality;
- driving at low speeds;
- sudden changes in the operating mode of the internal combustion engine;
- Frequent idling of the engine (for example, during traffic jams or warming up).
Red soot
If red spark plugs appear after unscrewing, then this type will turn out to be low-risk in most cases. The tonality of the surface appears in half of the cases and is explained by the presence of active impurities or additives in the mixture, which, for example, contribute to better combustion of the composition or protection from possible corrosion processes.
The presence of reddish-red tones is a sign of a large amount of fuel and the presence of oily elements in the mixture. The saturation of burgundy is a case associated with low-quality gasoline, which contains an abundance of improving additives. Light similar tones correspond to better quality gasoline.
If you detect a similar tone on the surface of the spark plug, you should not go to repair the car. It is enough to change the spark plugs, change the oil and refuel at another gas station.
What spark plug color is considered normal?
The normal color of spark plugs for regular vehicle use is light gray or taupe. A thin layer of plaque of this shade does not interfere with the operation of the internal combustion engine.
white deposits on spark plugs
... about spark plug diagnostics
Traces of erosion, melting or wear of the electrodes are an indication to replace the spare part, regardless of its color and service life.
Types of soot
Diagnostic operations can be carried out independently, based on the instructions for replacing spark plugs. It is advisable to carry them out regularly to monitor the condition of the fuel system elements. Otherwise, the car will behave negatively while driving, for example, there will be vibrations in the engine compartment, intermittent power, etc.
It is important to know what color spark plugs should be in order to fully perform their functions, because unnecessary deposits that hide shiny metal contact surfaces prevent a spark from appearing regularly at the right moment.
Before you find out what the color of spark plugs means, you need to understand what varieties there are. The following colors are found in cars:
The final color is determined by the chemical composition of the combustion mixture. An ideal working candle would be one that does not have a coating or has small whitish salt deposits, resulting in the formation of a gray film . Also, in addition to shades, there should not be a high density of soot, which often appears in the following cases:
- low quality fuel;
- problems working with filters;
- defective equipment from unscrupulous manufacturers;
- discrepancy between the physical characteristics of spark plugs and internal combustion engines.
Once the causes are identified, it is worth getting rid of them as soon as possible.
Causes of white spark plugs
The white deposit can be shiny, matte or raised, with growths on the central electrode. The most dangerous is a glossy coating, which includes a large number of metal particles. This condition of the spark plugs indicates constant overheating of the pistons and electrodes, which can lead to failure of the internal combustion engine.
A thin and matte light coating more often occurs when using low-quality fuel.
Incorrect fuel mixture adjustment
As the air supply to the fuel mixture increases, its ability to ignite decreases. This leads to problems with starting the engine, overheating of spark plugs and internal combustion engines, jolts and malfunctions while driving.
Driving with a lean mixture does not allow the engine to develop full power and leads to the appearance of a whitish coating on the electrodes. In addition to mechanical reasons (for example, gasoline leaks), provoking factors can be problems with sensors or an electronic unit that correlates the operating mode of the internal combustion engine and the characteristics of the fuel-air mass.
When the mixture becomes lean, it is recommended to check the throttle opening angle, the integrity of the gas tank and fuel line, the condition of the jet (for carburetors) and the fuel level. If the problem arose after changing gas stations, you should return to the previous brand of fuel.
... about the causes of white plaque
In rare cases, a light coating occurs due to the penetration of antifreeze into the internal combustion engine.
Air leak
Air leakage into the fuel mixture is another reason for its leanness. Most often the problem is found in the following areas:
- idle speed sensor seals;
- pipes connecting the manifold and the air filter;
- intake manifold (air penetration is explained by the appearance of cracks and depressurization).
The damaged part must be replaced immediately, because Constantly driving on a lean mixture causes excessive load on the engine and shortens its service life before major overhaul.
Injectors and fuel filters
A clogged fuel filter and insufficient pressure in the rail can prevent normal access of gasoline to the chamber. This also results in a too lean mixture, which provokes the formation of white soot.
When fuel filters are replaced irregularly or gasoline with a large amount of impurities is used, plaque is deposited on the walls of the fuel injectors, which reduces the diameter of the passage opening.
Manipulating the fuel system often helps eliminate the white layer on the electrodes of an injection engine.
Early ignition
Premature detonation of the fuel mixture leads to overheating of the spark plugs and the formation of deposits on the electrode. To eliminate plaque, you need to adjust the ignition moment by reducing the advance angle by 1-3°.
... about adjusting the ignition
In modern engines, this parameter is corrected automatically. Problems with ignition timing can occur due to software failures.
Incorrectly selected candles
The presence of white deposits may be due to the use of too “hot” electrodes. When choosing spark plugs with a low heat rating, regular overheating occurs, which provokes the appearance of light deposits.
You need to buy spare parts for the ignition system in accordance with the recommendations of the car manufacturer and the operating mode of the engine. For short trips at low speeds, you can choose “hotter” spark plugs, and for long trips and high loads, you can choose “cold” spark plugs.
Ignoring the problem will lead to the destruction of the electrodes in the cylinders, burnout of the piston rings and valves.
When analyzing the reasons, you need to understand that the color of the soot can also be explained by the type of fuel used. For example, for methane and propane-butane engines, white-gray spark plugs are the norm.
Other deposits and deposits
White plaque is not the only possible deviation from the normal state of the electrodes. To correctly assess risks, you need to know the meanings of other shades of deposits.
Black
The following problems can cause the appearance of black soot:
- Over-enriched mixture, fuel sensor problems (dry residue remains on the electrode).
- Unsuitable “cold” candles.
- Air filter clogged.
- Oil combustion (shiny, sooty electrode and thread).
- Loose nozzle fit or broken check valve.
With late ignition and a small advance angle, the spark plugs turn black even with the correct choice of heat rating and gasoline.
Red and brown
Scarlet, brown and red soot is a consequence of the use of low-quality fuel with ferrocene, manganese or lead additives. A thick red layer can make it difficult for a spark to pass through and disrupt the operation of the engine, so when it appears, it is recommended to change the brand of oil or gas station.
Zolny
Ash soot can be both light and dark. When it appears, increased oil consumption, decreased power, and darkening of the exhaust gases are observed.
The cause of the problem is worn or stuck piston rings.
Erosion
If the spark plug is defective, early ignition, or prolonged operation on low-octane or low-quality fuel, erosion (destruction) of the central electrode may occur. At the same time, the power of the internal combustion engine decreases, and when driving, jerking, instability at idle and “triple” are observed. The part requires immediate replacement.
Gasoline on spark plugs
Filling of spark plugs occurs when there is a malfunction of the fuel system, injector or carburetor, less often when starting in cold weather. To solve the problem, you need a complete diagnosis of the car and repair of damaged parts of the internal combustion engine.
Oil and fuel deposits
A shiny yellow or dark coating indicates grease penetration and wear of the valve seals. A characteristic accompanying symptom is blue smoke and high engine oil consumption.
Fuel carbon deposits occur when valves become depressurized or the piston system wears out. At the same time, against the backdrop of a drop in power and unstable operation of the internal combustion engine, gasoline consumption increases.
In more rare cases, a green coating is observed on the electrodes. Its cause may be the presence of additives in gasoline or the ingress of antifreeze into the combustion chamber.
Thread oil
Having unscrewed the spark plugs, we see an oil mark on the spark plug threads. The spark plug seal may be to blame here.
. Over time, it loses elasticity and begins to leak oil. This applies more to modern cars.
This sign may indicate the need to replace the valve stem seals.
They also lose elasticity over time and allow oil to pass through. The intake or exhaust valve guides may also "fit".
Malfunctions in
the crankcase ventilation system or turbocharger
. In all these cases, the engine may “eat” oil. But it will be insignificant, you will not notice it from the exhaust alone.
