What are the symptoms of insufficient engine cylinder pressure?

[LaMadeline]

Symptoms of insufficient engine cylinder pressure: 1. When turning the engine crankshaft with a hand crank, it feels effortless with no resistance, making it very difficult to start the engine; 2. The lubricating oil in the oil pan becomes dirty and overheats easily; 3. Excessive smoke escapes from the oil filler opening in the crankcase; 4. While driving, the engine feels underpowered, with increased fuel and lubricant consumption. Causes of low cylinder pressure: 1. Wear on the piston, piston rings, and cylinder, resulting in excessive clearance; 2. Increased end gap due to piston ring wear, reduced elasticity, or piston rings getting stuck in the ring groove, especially when the piston ring openings align in the same position within the cylinder; 3. Burned or damaged cylinder gasket, or loose cylinder head bolts; 4. Poor sealing between the valve and seat, insufficient valve clearance, broken or weak valve spring, or stuck valves; 5. Deformation of the cylinder head or block leading to poor sealing; 6. Incorrect valve timing.