What are the causes of insufficient cylinder pressure?

[StAutumn]

The main causes of insufficient pressure: air leakage between the cylinder head and the cylinder, air leakage between the spark plug sealing gasket and the cylinder head or a leaking pressure relief valve, air leakage in the crankcase, and air leakage caused by severe wear between the piston rings and the cylinder or stuck piston rings. The diagnostic method can be carried out in the following order: 1. Air leakage between the cylinder head and the cylinder: Turn the engine by stepping on it, and carefully observe whether there is oil foam at the joint surface between the cylinder head and the cylinder. If there is oil foam, it indicates air leakage at the cylinder head gasket. At this time, check whether the tightening nuts on the cylinder head are tightened. 2. If there is any looseness, tighten them evenly. If oil foam still appears after tightening, the cylinder head should be removed to check whether the cylinder gasket is damaged. If it is damaged, replace it with a new one.