What are the causes of low cylinder pressure?
2 Answers
Factors leading to low cylinder pressure include: 1. Air leakage between the cylinder head and the cylinder; 2. Air leakage between the spark plug sealing gasket and the cylinder head or leakage from the pressure relief valve; 3. Air leakage from the crankcase; 4. Severe wear between the piston rings and the cylinder or stuck piston rings causing air leakage. Diagnostic methods for insufficient cylinder pressure are: 1. Unstable engine operation, popping sounds from the exhaust pipe or backfiring in the carburetor; 2. Difficulty in cold starts, with no significant change when climbing hills; 3. Water droplets discharged from the exhaust pipe, backfiring in the carburetor, or water leakage into or out of the crankcase. A cylinder refers to a cylindrical metal component that guides the piston in linear reciprocating motion inside the cylinder. It is categorized into: single-acting cylinders, double-acting cylinders, diaphragm cylinders, and impact cylinders.
Low cylinder pressure? I've encountered this issue before. When driving my old car, it felt sluggish and shaky. After towing it to the repair shop, the mechanic measured the pressure and found it was insufficient. Common causes include valve problems, where worn valve seats fail to seal properly, leading to air leakage during compression; worn or broken piston rings also cause air leakage, allowing gas to escape into the oil pan; if the cylinder walls are scratched or cracked, high-pressure gas will leak out; and a deteriorated or damaged cylinder head gasket can cause leaks at the connection points. The repairs aren’t too difficult, but don’t ignore it—otherwise, the engine may burn oil or even be ruined. In my case, replacing the piston rings and valves improved the situation. Regular maintenance, like monitoring the oil condition, can help prevent this. In short, get it checked at a professional shop as soon as possible.
