What are the causes of insufficient cylinder compression?

[LeCora]

The causes of insufficient cylinder compression: 1. Severe wear of piston rings, leading to reduced sealing effectiveness: Among these, insufficient cylinder compression caused by piston ring wear is a common occurrence in older vehicles. The oil ring's function is to distribute the oil flung up by the crankshaft onto the cylinder walls to lubricate and reduce wear between the cylinder walls and piston rings. 2. Abnormal wear such as scoring or unevenness on the cylinder walls: Cylinder wall scoring is caused by carbon deposits or other foreign objects entering the cylinder, which then scrape the cylinder walls as the piston moves. 3. Poor sealing of the valve seats or spark plug seats: Poor sealing of the spark plug seat is often due to damaged threads caused by excessive torque during spark plug installation. Modern engines use aluminum cylinder heads, which are more susceptible to thread damage.