What Causes No Cylinder Compression in an Engine?
2 Answers
When a cylinder compresses, a certain pressure is generated inside it, which is called cylinder compression. No cylinder compression means the cylinder is not sealed, and pressure cannot be formed during compression. There are many reasons for no cylinder compression, such as valve breakage, cylinder scoring, cylinder gasket damage, etc. Below are detailed explanations: 1. Four-stroke engines: Mainly due to valve leakage, excessive clearance between the piston, piston rings, and cylinder block, cylinder gasket leakage, or the use of non-standard or mismatched parts like pistons, leading to reduced compression ratio and pressure drop. 2. Two-stroke engines: Primarily caused by wear of the cylinder block, piston, piston rings, crankshaft oil seal leakage, reed valve leakage, or cylinder gasket leakage.
I've repaired many engines with no cylinder compression, and the most common issue is problems with valve sealing, excessive valve clearance, or carbon buildup causing the valves not to close tightly. Worn or broken piston rings are also very common, especially in cars with poor oil quality, leading to cylinder leakage. Another common issue is a damaged cylinder head gasket, which often occurs after the engine overheats, and you can see bubbles in the radiator or emulsified oil. Once, I encountered a car where the timing belt skipped three teeth, directly bending the valves. The most troublesome issue is cylinder scoring, where the piston leaves deep marks on the cylinder wall—this requires replacing the engine block. Always measure the compression ratio first to confirm the problem before disassembling the engine blindly.
