What are the two types of cylinder liners?
4 Answers
Cylinder liners are divided into dry cylinder liners and wet cylinder liners, with the distinction primarily based on whether they come into contact with coolant. Generally, wet cylinder liners have a wall thickness of 5 to 8 mm, while dry cylinder liners have a wall thickness of 1 to 3 mm. Dry cylinder liners are commonly used in gasoline engines, and some low-horsepower diesel engines also employ dry cylinder liners. Wet cylinder liners are used in diesel engines. A cylinder liner is a cylindrical component placed within the cylinder bore of the engine block, secured at the top by the cylinder head, with the piston performing reciprocating motion inside its bore. The outer surface is cooled by circulating water. The inner surface of the cylinder liner is directly exposed to high-temperature, high-pressure combustion gases and continuously undergoes high-speed sliding friction with the piston rings and piston skirt.
When I previously researched engines, I paid special attention to cylinder liners, which commonly come in two types: dry and wet. A dry cylinder liner is like a thin metal sleeve pressed directly into the engine block, with no contact with coolant on the outside. It has a compact structure but poorer heat dissipation. Wet liners, on the other hand, have their outer walls directly immersed in coolant, with thicker sleeve walls and rubber sealing rings to prevent leaks. Mechanics dread wet liner leaks the most, as they require disassembling the engine to replace the seals. While dry liners save space, repairing them after wear involves re-boring the entire block, which can be more costly. Nowadays, many high-performance engines use dry liners, while ordinary family cars mostly use wet liners.
A friend once asked me about cylinder liner issues encountered during car repairs, and there are generally two common types. Dry cylinder liners are like the engine's undershirt—a metal sleeve directly pressed into the cylinder block bore, requiring a hydraulic press for installation and removal, with heat dissipation relying entirely on metal conduction. Wet cylinder liners, on the other hand, are like a sports jacket with water-cooling functionality—their outer walls contact the coolant, sealed by upper and lower rubber rings to prevent leakage. While they offer direct cooling efficiency, the risk of coolant leakage is higher. Last time my car had abnormal water temperature, it was due to aging seals on the wet cylinder liner, allowing coolant to mix with the engine oil, triggering all dashboard warning lights. It cost over 5,000 yuan for a major overhaul. The choice between them depends on the engine design requirements.
Cylinder liners are divided into dry and wet types, a key topic in engine studies. Dry liners have thin walls and are press-fitted into the cylinder block bore, relying entirely on metal conduction for heat transfer. Wet liners have their outer walls in direct contact with coolant, sealed at the bottom with copper gaskets and at the top with flanges, offering extremely high heat exchange efficiency but requiring careful sealing. Once, during a racing car modification, cast iron dry liners were used, leading to cylinder scoring due to block deformation at high RPMs. Switching to chrome-plated wet liners later stabilized heat dissipation. During maintenance, dry liners require cylinder boring, while wet liners allow for easier direct replacement with kits.
