What Are the Causes of Excessive Cylinder Pressure?

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The main causes of excessive cylinder pressure are the following two points: 1. Excessive carbon deposits in the combustion chamber; 2. During repairs, excessive grinding of the cylinder head and cylinder block mating surfaces leads to a reduced combustion chamber volume and an excessively high compression ratio. Below are specific details regarding cylinder wear: 1. Mechanical wear. When the piston is at top dead center, the high-temperature gas explosion pressure is at its maximum, causing increased piston ring pressure on the cylinder wall, increased friction, and destruction of the lubricating oil film. The cylinder wall corresponding to the first piston ring experiences the most severe wear. 2. Corrosive wear. Organic acids and acidic oxides (which dissolve in water to form mineral acids) generated during the combustion of the air-fuel mixture corrode the cylinder surface, leading to corrosive wear. The upper part of the cylinder block is not fully covered by the lubricating oil film, making corrosion more severe. 3. Abrasive wear. Dust from the air, mechanical impurities in the lubricating oil, and wear particles in the engine enter between the cylinder walls, causing abrasive wear. Dust from the air is drawn into the upper part of the cylinder, and its sharp edges result in the greatest wear in the upper cylinder section.