Is a Car with Replaced Piston Rings Still Worth Buying?
1 Answers
A car with replaced piston rings can still be used. Replacing piston rings does not necessarily indicate severe engine damage. The key factors in determining engine condition are fuel consumption, responsiveness, and whether the engine oil shows signs of emulsification. The functions of piston rings include sealing, oil control, heat conduction, and guidance. Sealing: The primary function of piston rings is to maintain a seal between the piston and cylinder wall, minimizing gas leakage. This is mainly achieved by the compression rings, ensuring that under any operating conditions, the leakage of compressed air and combustion gases is minimized to improve thermal efficiency; prevent seizure between the cylinder and piston or cylinder and rings due to gas leakage; and avoid issues caused by lubricant degradation. Oil Control: Piston rings properly scrape off excess oil adhering to the cylinder wall, maintaining normal oil consumption. If too much oil is supplied, it can be drawn into the combustion chamber, increasing oil consumption and causing carbon deposits from combustion, which severely impacts engine performance. Heat Conduction: Piston rings transfer the high heat generated by combustion to the cylinder wall, thereby cooling the piston. The heat dissipated through the piston rings to the cylinder wall typically accounts for 30-40% of the heat absorbed by the piston top. Support: Since the piston is slightly smaller than the cylinder bore, without piston rings, the piston would be unstable inside the cylinder and unable to move freely. Additionally, the rings prevent direct contact between the piston and cylinder, providing support. Piston rings are divided into two types: compression rings and oil rings. Compression rings seal the combustible gas mixture in the combustion chamber, while oil rings scrape off excess oil from the cylinder walls.
