Carbon deposits are a mixture that builds up on the engine’s valves, combustion chambers and intake pipes. It is caused by the insufficient combustion of engine oil, under the catalysis of high temperature and oxygen, hydrochloric acid and resinous colloids are formed, adhered to the surface of parts, and then further condensed into asphaltenes and oil cokes under high temperature. mixture.
Carbon deposits can be divided into valves, combustion chamber carbon deposits and intake pipe carbon deposits. Carbon deposition is very harmful to the engine, so it needs to be prevented and removed in time.
Causes of Carbon Deposits
1. During the normal operation of the engine, gasoline and engine oil normally entering the combustion chamber cannot be completely combusted in the cylinder under the condition of insufficient oxygen supply, resulting in soot and burnt particles of lubricating oil. When the engine continues to run, it is further oxidized and becomes colloid. Sticks firmly to the piston crown, piston rings, back of the valve, inner surface of the intake pipe, throttle body and combustion chamber, etc. Under the repeated action of high temperature, the colloid is turned into asphaltene, resinous and carbonaceous, thus forming carbon deposits.
2. Crankcase ventilation settings. In order to prevent polluting the air, automobile design engineers directly introduce the exhaust gas inside the engine into the intake manifold, and enter the combustion chamber together with the fresh air for combustion. The high-temperature oil vapor fills the intake manifold together with the fresh air, part of which adheres to the tube wall and the back of the valve, and the other part follows the intake airflow and mixes with the injected fuel at the intake valve to form a mixture, which enters the combustion chamber and is discharged after combustion outside the car.
3. During the storage and transportation of gasoline, it is easy to oxidize with air to form colloidal substances, or the content of colloids in gasoline itself is very high (gasoline quality is poor), and these colloids enter with gasoline through the fuel supply system of the vehicle Inside the combustion chamber, after burning with gasoline, a lot of carbon deposits and oil stains will be generated on the fuel injector in the fuel supply system, the combustion chamber of the engine, the piston ring groove, the spark plug, the back of the intake valve, the intake passage, etc. Wait.
4. Congested urban road conditions keep the vehicle in a stop-and-go state all the time, the engine cannot run at a high speed, and the fuel or lubricating oil that has entered the combustion chamber cannot be 100% burned. The unburned part of the fuel is under the action of high temperature and oxygen Colloid is formed under the environment, adheres to the surface of parts inside the engine, and then forms carbon deposits through high temperature.
5. Determined by the control characteristics of the EFI engine, every time the cylinder works, it injects fuel first and then ignites. When we turn off the engine, the ignition is cut off immediately, but the gasoline injected by this working cycle cannot be ignited. Recycling can only be attached to the intake valve and the wall of the combustion chamber. Gasoline is easy to volatilize, but the wax and gum in gasoline remain. Over time, the wax and gum in gasoline accumulate thicker and thicker, repeatedly When heated, hardens to form carbon deposits. When there is too much carbon deposit in the engine, it will cause the engine to work poorly and produce different failure phenomena.
The effect of carbon deposits on the engine
The carbon deposits in the combustion chamber have a great impact on the normal operation of the engine, such as causing the valve to close tightly, air leakage from the intake valve or exhaust valve, knocking, etc. Especially for knocking, when the carbon deposit is serious, the actual volume of the cylinder becomes smaller and the compression ratio increases. At the same time, in a high temperature environment, the carbon deposit will always burn red due to poor heat dissipation. In this way, the high-temperature compressed mixture is ignited by the timing spark plug. , It can also be randomly ignited by the high-temperature carbon deposits in the cylinder, resulting in knocking.
Measures to reduce, prevent and remove carbon deposits
Fill with high-quality gasoline
Impurities such as wax and colloid in gasoline are the main components of carbon deposits, so gasoline with high cleanliness has a weaker tendency to form carbon deposits. Unfortunately, the quality of gasoline in our country is still low compared with developed countries, so it can only be crude. Everyone should note that high grades do not mean high quality, that is to say, No. 97 oil does not necessarily have less impurities than No. 93. The grade only represents the octane number of the oil, and does not represent the oil quality and cleanliness.
In order to ensure the cleanliness of gasoline, some car owners will add gasoline detergent to gasoline. This can effectively prevent the formation of carbon deposits on the metal surface, and gradually activate the original carbon deposits and slowly remove them, thereby protecting the engine from damage. However, the addition of gasoline cleaners must be cautious. If fake and inferior products are added, the opposite effect will be obtained.
Reduce idling time
If the idle time is long, the time for the engine to reach normal temperature will be longer, and the gasoline will evaporate slowly after being sprayed to the back of the valve, and carbon deposits will also be generated. At the same time, if you often drive at idle speed, the air flow into the engine will be small, so that the flushing effect on carbon deposits will become weaker, which will promote the deposition of carbon deposits.
Run more at high speed
The purpose of running more at high speed is to use the airflow to scour the air intake to prevent carbon deposition. In addition, increasing the speed of shifting gears has the same effect as multi-speed high-speed running. Changing the original gear shifting at 2000 speeds to 2500 speeds can not only effectively prevent carbon deposits, but also improve the power of the car and avoid shifting. Protect the engine from knocking caused by low gear speed.
Use Fuel Cleaning Wash Additives
It is quite simple to clean the engine with cleaning and protecting agent. Please refer to the product instructions for specific usage methods and precautions. When the engine is working, the cleaning agent is sucked into the fuel supply pipeline together with the fuel by the fuel pump. With the flow of fuel, it can not only clean the glue in the fuel tank, the glue on the gasoline pump filter, and the glue and carbon deposits on the fuel injector, but also automatically clean the valve and the engine cylinder when the engine is working normally. The carbon deposits in the engine make the engine “rejuvenate” and rejuvenate the surging power. Since the glue cleaned from the fuel tank, fuel pump filter and fuel pipeline will deposit in the fuel filter, the fuel filter (gasoline grid) must be replaced in time after cleaning without disassembly.
I need to remind car owners again that because the chemical cleaning ingredients in the cleaning agent have a certain corrosive effect on the rubber oil supply pipeline, when using this method, you must pay attention to the use cycle and interval time, otherwise it will speed up the fuel rubber oil supply pipeline. of aging and corrosion.
Disassemble and clean
“No dismantling and cleaning” is simple and labor-saving, just use it in the correct way. But for engines with serious carbon deposits, this method seems powerless and cannot achieve the purpose of complete cleaning. After “cleaning without dismantling”, if the engine performance is still poor, and the technician tells you that the problem is caused by too much carbon deposit in the valve and cylinder, then you have to disassemble the engine to solve it.
The cleaning of carbon deposits on the valve is relatively simple. After the intake manifold is removed, it can be removed by hand or soaked in cleaning drugs. As for the cleaning of carbon deposits in the engine cylinder, it is necessary to “go to war” and remove the cylinder head, timing belt, etc. before cleaning.
After the engine is disassembled and reassembled, its power and sealing performance will be inferior to those of the original factory, so in general, it is not suitable to clean the carbon deposits in the engine cylinder frequently. As a last resort, you must also go to a regular repair shop, otherwise the engine performance will be greatly reduced.
