White carbon deposits on spark plugs
Content
Spark plugs operate in an aggressive high-temperature environment. This leads to the formation of a thin light gray, beige, yellowish or brown soot on them. The color is given by fuel impurities and iron oxide, which is formed when oxygen is exposed to the steel case. The color and texture of deposits change in case of malfunctions. If there is white carbon deposits on the spark plugs, there is probably a malfunction in the power or ignition system, or the wrong fuel is being used. To figure out why there is white soot on the candles, to accurately determine the root cause and eliminate it, our guide will help.
Why does white soot appear on candles
The reason for the formation of white carbon deposits on the candles is overheating as a result of a violation of the ignition process due to a sub-optimal ratio of gasoline to air or a missed ignition. Due to the effect of elevated temperatures, dark carbon-containing deposits burn out, while more persistent light ones remain.
The study of the formations will allow you to understand what the white soot on the spark plug electrode means. Heterogeneous, shiny and massive rough plaque are different in nature.
What causes a mild white soot?
Weak white soot on the spark plug - may be a false alarm. Quite a typical phenomenon is a slight white soot on candles after installing gas.
Light white soot of candles is not always a sign of a problem
Gas does not contain special additives that improve its properties, in such quantities as gasoline. Its combustion temperature is slightly higher, and soot is practically not formed. Therefore, a small white soot on candles in a car with LPG is normal.
Mild white coating on vehicles without gas installation indicates an unstable mixture or the use of undesirable fuel additives. For example, leaded gasoline containing a lead additive can leave a silvery white deposit. Failures of the carburetor or injector sensors can also cause a whitish coating.
Reasons for the formation of white soot on spark plugs
| Cause of thin white soot | What does it affect? | What needs to be produced? |
|---|---|---|
| Worn spark plugs and low quality gasoline | The cycle of operation of the internal combustion engine is disrupted, the loads on the CPG, KShM, etc. increase. The resource of the internal combustion engine is significantly reduced | Refuel with high-quality fuel, ignite and clean, or replace candles |
| Low-quality fuel (old settled gasoline, diluted fuel, counterfeit gasoline from thermal power plants, etc.) | The stability of the motor is disturbed, the production of parts is accelerated, and the risk of breakdown increases. When using counterfeit gasoline with TES additive (tetraethyl lead), the lambda probe and the injection engine catalyst fail | Drain low-quality fuel, fill in normal gasoline from a proven gas station. Ignite and clean or replace spark plugs |
| low octane fuel | The risk of detonation of the mixture increases, the wear of the internal combustion engine accelerates many times. Pistons, connecting rods, pins, valves and other parts suffer from shock loads | Refuel with high-quality gasoline with OC, provided by the car manufacturer. Clean or change spark plugs |
| Unstable fuel-air mixture | The internal combustion engine cannot reach a normal working rhythm, the parts are subjected to load fluctuations and wear out faster | Check the operation of the carburetor or injector sensors (DMRV, DTV and DBP), nozzles, intake tightness |
Why does white glossy soot appear on candles?
By itself, a thin white glossy soot on spark plugs does not adversely affect the operation of the internal combustion engine, but indicates the presence of a number of problems. On an old car, white spark plugs - the carburetor, with a high probability, incorrectly forms a mixture. Possible reasons for this are:
- contamination of the throttle valve;
- clogging or incorrectly selected jet diameter;
- incorrect ignition timing;
- air leak between carburetor and intake manifold.
On modern cars, other reasons for the formation of white soot on spark plugs are more common: the injector doses fuel and sets the UOZ based on ECU firmware algorithms. First, it is worth checking the motor for suction, for example, using a smoke generator. When unaccounted for air bypasses the mass air flow sensor (DMRV) or the absolute pressure sensor (MAP), the ECU cannot correctly dose gasoline and adjust the UOZ to the actual composition of the mixture. In the absence of leaks, it is necessary to diagnose the DMRV, DBP and the air temperature sensor (DTV). An excessively lean mixture is indicated by ECU errors P0171, P1124, P1135 and P1137.
Where does the white glossy coating come from on the candles: a table of reasons
| Cause of glossy white soot | What does it affect? | What needs to be produced? |
|---|---|---|
| Lean fuel mixture | Overheating of cylinders and valves, increased wear of pistons, rings and cylinder walls, accelerated degradation of engine oil, reduction in ICE power and thrust | Adjust the UOZ and check the carburetor / injector sensors, diagnose the intake for air leaks |
| Intake air leaks | The mixture becomes lean, the consequences of which see the previous paragraph | Check the intake system (pipes, reservoir and intake manifold gaskets, injector seals) for leaks, for example, using smoke, restore tightness |
| Clogged injector nozzles | The motor actually receives less fuel than the ECU “thinks”, as a result, the mixture becomes leaner, the consequences of which, see above | Diagnose the injectors of the injection system, clean and flush them, and, if necessary, replace them with new ones |
| Untimely sparking due to incorrectly configured ignition | The internal combustion engine loses traction, overheats, accelerates its wear, increases the risk of burnout of valves and other exhaust elements, destruction of the catalyst | Check the sensor marks, timing belt installation, adjust the ignition system. For cars with LPG, it is advisable to install a UOZ variator or dual-mode ECU firmware for gas to correct ignition angles |
| wrong spark plug | Deterioration of sparking, overheating of candles and their accelerated wear, loss of traction | Replace spark plugs by selecting a part with a heat rating provided by the manufacturer |
| The octane number of the fuel is lower or higher than the desired | Deterioration of ignition, loss of traction. Detonation and accelerated wear of the connecting rod and piston group, if the OCH is too low. Overheating of exhaust elements, burnout of valves, failure of the catalyst if the RH is too high | Drain low-quality gasoline and fill with normal. On an old car designed for low-octane fuel, as well as when using LPG (especially methane, whose octane is about 110) - adjust the ignition for the new fuel, use the UOZ variator to correct when using gas |
White velvet soot on candles - what is happening?
A thick, rough soot on white candles indicates that foreign substances, such as antifreeze or oil, have entered the combustion chamber.
The detection of a thick white coating indicates the need for urgent motor diagnostics. So timely replacement of valve seals or cylinder head gaskets will help to avoid costly repairs.
A velvety thick white coating on the spark plug may be due to antifreeze or excess oil.
also one example of thick and velvety white soot due to excess oil
Thin white soot, which has a velvety texture, as is the case with glossy (slightly shiny) deposits, usually indicates incorrect mixture formation or untimely spark supply. Its causes depend on the type of power supply system.
Fine matte carbon deposits through early ignition
If on an old car you see a thin velvety white deposit on the spark plugs, the carburetor needs to be checked. The jet is probably clogged or the settings are off. It is also advisable to check the distributor and other elements of the ignition system, because early ignition may also be the culprit.
Light deposits are also formed due to additives and impurities in the fuel. At the same time, it is worth checking if there is an excessive consumption of oil, if antifreeze is leaving.
On more modern cars, when you see white soot on the spark plugs, the injector needs to be diagnosed using OBD-2. there is also one purely injection culprit - nozzles that, when clogged or worn, do not dose fuel correctly.
Causes of white velvet coating on candles
| Cause of velvety white soot | What does it affect? | What needs to be produced? |
|---|---|---|
| Incorrect spark plug operation, lack of energy for a spark | an incorrectly selected spark plug cannot ensure the normal operation of the internal combustion engine, which is why it is unstable and wears out faster | Replace candles by selecting the appropriate ones according to the manufacturer's catalog |
| Ignition system problems | Check coil(s), high-voltage wires, distributor (for machines with distributor), replace faulty parts | |
| Incorrect adjustment of the fuel injection system | Incorrect quantity-quality of fuel due to incorrect setting or clogging of the carburetor | Check carburetor adjustment, clean or replace |
| On the injector, the ECU doses the mixture incorrectly due to incorrect sensor readings or malfunction of the injectors | Carry out OBD-2 diagnostics, check the correctness of the readings of the MAF or DBP and DTV, lambda probe, diagnose the injectors. Defective parts - replace | |
| Air leaks appear in the intake system due to leaks, the mixture becomes leaner and the engine overheats, valves can burn out and wear accelerates | Check the intake system for leaks using a smoke generator | |
| Clogged fuel filter | The flow of gasoline is reduced, the mixture is depleted. Traction is lost, engine wear accelerates | Replace fuel filter |
| Leaky cylinder head gasket or violation of the integrity of the channels | Violation of the integrity of the cylinder head gasket or channels leads to the fact that coolant enters the combustion chamber. In this case, oil can get into antifreeze or vice versa. The internal combustion engine cannot work normally, an emulsion forms in the crankcase, there is a shortage of lubrication and overheating, the internal combustion engine quickly fails | Check for bubbles in the coolant expansion tank while the engine is running. Check for changes in antifreeze level. Check the oil for the presence of a light emulsion. If there are problems, remove the cylinder head, debug it, if necessary, repair it and replace the gasket |
| Too much oil enters the combustion chamber | The pressure of the crankcase gases due to a drop in compression drives oil into the intake. Sparking worsens, wear of the internal combustion engine accelerates, smoke comes out of the exhaust | Check the oil separator in the cylinder head, if it breaks (for example, falls off), repair it. If the reason is the wear of the rings and pistons, disassemble and defect the motor, carry out a partial or complete overhaul |
| The oil scraper piston rings cannot cope with the removal of excess lubricant from the cylinder walls, the exhaust smokes, oil burns appear | Carry out decarbonization of the internal combustion engine, if it does not help, disassemble and defect the internal combustion engine, repair the CPG, change the rings (at least) and clean the pistons | |
| Valve seals have lost elasticity. Oil consumption rises, smoke appears, operation stability is lost and wear of the internal combustion engine accelerates | Replace seals |
How to properly check spark plugs for white soot
The color of soot on candles allows you to prevent serious problems in a timely manner, so you need to periodically check their condition. In order to check spark plugs for white soot, you will need:
- candle key (usually a deep head of 16 or 21 mm);
- flashlight (in order to take a closer look at soot in case of lack of light);
- rags (in order to wipe the wells of the candles before removing them, and also to close them for the duration of the check).
The procedure is simple and will take about 10 minutes. This is enough to detect white soot on spark plugs: an injector, HBO or carburetor - it does not matter, since the manipulations are the same. The only difference is that in some models it will be necessary to first remove the high-voltage wires from the candles, while in others the individual coils that are fastened with screws will additionally require an appropriate ring wrench or a head with a knob.
How to clean spark plugs from white soot
If there is a little deposits, cleaning the candles from white soot will allow them to continue their operation and avoid immediate replacement. There are two effective ways to remove plaque: mechanical and chemical, we will discuss each of them in more detail below.
We get rid of white soot mechanically
Before cleaning carbon deposits on a spark plug, you should choose the right abrasive. To remove small deposits from the electrodes, the following are suitable:
Cleaning carbon deposits with fine-grained sandpaper
- thick metal brush to remove rust (manual or nozzle on a drill);
- fine-grained (P240 and above) emery skin.
The first step is to remove the candle and rub it with a brush with metal threads to remove deposits. Plaque in the gap between the electrodes can be carefully cleaned with a fine sandpaper, folding it in half. In this case, you should be careful: with the correct cleaning of the spark plugs, there should be no scratches.
If white soot appears on new candles, although HBO is not installed on the car, before cleaning it, check whether the candle fits the engine in terms of glow number. If the part is selected incorrectly, it makes no sense to clean it - an immediate replacement is required.
We remove white soot with candles chemistry
also one way to remove plaque is to chemically clean the candle from carbon deposits. For it, you can use various highly active means:
- organic solvents (carb cleaner, gasoline, kerosene, acetone, paint thinners, dimexide);
- rust converter or phosphoric acid solution;
- vinegar or ammonium acetate solution 20%;
- means for cleaning plumbing and removing plaque (like Cillit).
The chemical method is more preferable, since it is possible to clean the candle from plaque with chemistry without damaging its electrodes. This is especially important for expensive spark plugs with precious metals, the thin layer of which is easily damaged by abrasives. Chemical cleaning of a candle from white plaque is done as follows:
Cleaning candles from soot chemically
- We process the candle with a solvent to degrease it.
- We place the working part in a cleaning agent.
- We withstand from 10 minutes to several hours, controlling the rate of carbon removal.
- Wash the candle again with solvent.
After removing carbon deposits, the candles can be dried and installed in the engine. To speed up chemical reactions, non-flammable liquids can be heated, but not brought to a boil. Dimexide must be heated, because it begins to solidify already at room temperature.
Thermal cleaning of candles, that is, calcination, is not very effective in itself, because white soot is heat resistant. But it can be successfully used in conjunction with mechanical or dry cleaning, periodically heating the electrodes over a fire for 1–5 minutes, depending on the degree of contamination.
How to prevent white soot on spark plugs
Timely maintenance of spark plugs allows you to extend their life, but it is much more important to eliminate the causes of plaque:
When soot appears on new candles, an urgent diagnosis must be carried out
- If new candles are quickly covered with soot, you need to diagnose the power system, adjust the carburetor or change the injector sensors, check and clean the nozzles.
- If deposits form while driving on gas, you need to use a UOZ variator or install a dual-mode firmware for gas and gasoline.
- in order to avoid overheating, you need to control the level of antifreeze, change it at the end of its service life.
- If soot on white candles appears after refueling at a dubious gas station, change the fuel and do not refuel there in the future.
- Use quality engine oils to reduce deposits.
- in order to extend the service life of the parts of the power system, reduce the interval for changing the fuel and air filters by 2–3 times (up to 10–15 thousand km).
Found black and white soot on candles or other unusual deposits - do not delay the diagnosis. This will avoid fatal consequences for the motor.
