A diagnostic procedure used to assess the condition of an internal combustion engine’s cylinders by measuring the rate at which compressed air escapes. During this test, each cylinder is pressurized, and the percentage of air loss is measured. This leakage indicates the effectiveness of the piston rings, valves, and cylinder head gasket in maintaining combustion pressure. For example, a high percentage of air loss from a cylinder during this evaluation signifies potential wear or damage to these components, impacting engine performance and efficiency.
The value of this diagnostic method lies in its ability to pinpoint the source of compression loss, which can be detrimental to fuel economy, power output, and overall engine health. Identifying issues early through this testing allows for timely repairs, preventing more extensive and costly damage. Historically, this type of assessment has been a staple in engine maintenance, evolving with technological advancements to provide increasingly accurate and efficient diagnostics.