What are the causes of low cylinder compression pressure?
2 Answers
Cylinder compression pressure being too low is mainly caused by air leakage between the cylinder head and the cylinder. Here is some related information about cylinder compression: 1. Compression ratio: The engine compression ratio refers to the degree to which the engine's air-fuel mixture is compressed, expressed as the ratio of the total cylinder volume before compression to the cylinder volume after compression (i.e., the combustion chamber volume). 2. Cylinder function: The cylinder is a cylindrical metal component that guides the piston to perform linear reciprocating motion inside it. In an engine cylinder, air converts thermal energy into mechanical energy through expansion; in a compressor cylinder, gas receives compression from the piston to increase pressure.
I've seen low cylinder compression pressure many times. When repairing cars, the most common causes are severe piston ring wear causing air leakage, and poor valve sealing, such as valve seat erosion or improper valve clearance leading to incomplete closure. A leaking cylinder head gasket due to aging can also cause pressure drop, which is a major hazard affecting engine power, increasing fuel consumption, and even making the car difficult to start. Additionally, cylinder wall wear or scratches can reduce compression efficiency. Don't forget issues like timing chain misalignment, which can cause valve timing disorder. It's recommended to first use a compression tester to measure each cylinder's data and compare it with normal values. If the deviation is large, take it to a professional shop for inspection and parts replacement, rather than waiting for the problem to worsen and cost more.
