​How to stop carbon build up in diesel engine?

Carbon deposit not only affects the heat dissipation of the diesel engine, and causes the diesel engine to overheat, but also increases the compression ratio of the diesel engine, which makes the diesel engine work worse and lowers its power. Remind users to reduce carbon deposits during use, and to completely remove carbon deposits during major repairs. As the diesel engine's use time increases, the carbon deposits on parts such as the combustion chamber, the top of the piston, and the exhaust pipe will also become thicker. Carbon deposits not only hinder the heat dissipation of the combustion chamber and piston but also reduce the volume of the combustion chamber, which reduces the power of the diesel engine and increases fuel consumption. It must be removed when the diesel engine is repaired. The following analyzes the causes and hazards of diesel engine carbon deposits and proposes methods to prevent and remove carbon deposits.

Causes of Diesel Engine Carbon Deposit

The hazards of carbon deposits

Ways to prevent carbon deposits in diesel engines

Causes of Diesel Engine Carbon Deposit

Diesel engine carbon deposits are the product of incomplete combustion of fuel and lubricating oil. Its production is closely related to the environmental conditions of the use of fuel and lubricating oil and its quality. All influencing factors that cause incomplete fuel combustion and abnormal entry of lubricating oil into high-temperature parts of the engine are the reasons for the formation of carbon deposits. The main reasons for the formation of carbon deposits in diesel engines are as follows: ①Diesel is of poor quality and contains impurities. ②The lubricating oil in the diesel engine has been used for too long and the content of jelly is high. ③The piston ring is loose, the opening is too large, and the gap between the valve guide and the valve stem is too large, causing the oil to escape into the combustion chamber and burn. ④The ignition timing is too early or too late, and the fuel injection pump supplies too much fuel. ⑤The diesel engine runs at low temperature for a long time or the cylinder seal is worn or damaged, which makes the fuel combustion incomplete. ⑥Injector pressure is too low, poor atomization, oil dripping, and oil leakage. ⑦Diesel engine is overloaded for a long time or the driver often hits the throttle.

The hazards of carbon deposits

(1) Increase the compression ratio of the diesel engine. Excessive adhesion of carbon deposits on the cylinder wall and piston will reduce the volume of the combustion chamber and increase the compression ratio, resulting in a decrease in the power of the diesel engine. It is also easy to cause diesel engine deflagration, knock, damage parts, and shorten the service life of diesel engines.

(2) Increase the temperature of the diesel engine. Carbon deposition is a poor conductor of heat. When the combustion chamber and the top of the piston are covered with a layer of carbon deposition, the heat of the diesel engine cannot be dissipated in time, causing the temperature of the diesel engine to increase sharply. Diesel engine overheating will cause many undesirable effects on its work, such as deterioration of lubricating oil, increased wear and tear, thermal deformation of mechanical parts, and jamming.

(3) Carbon deposits on the working surface of the valve and its seat ring will cause the valve to not close tightly and cause air leakage; when the valve guide and valve stem are carbonized and glued, it will accelerate the wear between the valve stem and the valve guide.

(4) If carbon deposits adhere to the injector nozzle, it will cause the nozzle hole to be blocked or the needle valve to jam, resulting in poor fuel atomization and incomplete combustion.

(5) When carbon deposits in the piston ring groove, the side clearance and backlash of the piston ring will become smaller, or even no gap. At this time, it is very easy to cause the piston ring to cement and lose its elasticity, pulling the cylinder, or even breaking the piston ring.

(6) When carbon deposits on the inner wall of the exhaust duct and exhaust pipe muffler are serious, the exhaust resistance of the diesel engine will increase, the exhaust resistance in the cylinder will increase, and the exhaust will not be clean.

Ways to prevent carbon deposits in diesel engines

Chemical removal of carbon deposits is to use chemical solvents (carburizes) to soften the carbon deposits on the surface of the parts, and the softened carbon deposits can be easily removed. Decarbonizing agents can be divided into inorganic decarbonizing agents and organic decarbonizing agents according to their properties. Inorganic decarbonizing agents include alkali metal soaps and alkalis. Alkali metal soaps include various soaps, potassium oleate, oleic acid, and alkaline synthetic detergents. Alkali substances include caustic soda, trisodium phosphate, money hydroxide, and carbonic acid, etc. This type of decarbonizer has low cost and low toxicity, and can also dissolve some hard carbon deposits. In particular, ammonia and caustic soda have special effects on dissolving hard carbon deposits on steel parts, but they are highly corrosive to non-ferrous metals, so they can only remove carbon deposits on steel parts. When removing carbon deposits with an inorganic decarburizing agent, the temperature of the solution is 80～95℃, and the parts are immersed in the solution for 2～3 hours. After the carbon is fully softened, wipe with a brush to remove the carbon deposits, and then clean the parts with hot water (add 0.1% to 0.3% potassium dichromate to the water), then blow dry with compressed air. Inorganic solvents use water as a diluent to dilute thicker solvents or dissolve solids, reducing the cost of the solution. Inorganic solvents are commonly used as buffers such as sodium silicate, chromate, or dichromate to prevent the alkali components of the solution from corroding non-ferrous metals. The amount is generally 0.1% to 0.5% of the solution. Too much dosage will reduce the carbon removal effect, while too little dosage will not have the necessary buffering effect. Inorganic solvents often use potassium soap and triethanol as active agents to reduce the surface tension of the solution and make the solution contact and adsorb carbon deposits well. Inorganic solvents have the advantages of low toxicity and low cost, but the decarbonization effect is poor.

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