What does a cylinder leak down gauge measure?

A cylinder leak down gauge is specifically designed to assess how well the cylinders in an engine are sealed. It functions by measuring the amount of air that escapes from the combustion chamber when a certain amount of compressed air is applied. An efficient seal within the cylinder will prevent or minimize the air from leaking out, which indicates that the piston rings, valves, and other sealing components are functioning properly.

If there is a significant leakage, it may suggest issues such as worn piston rings, leaking valves, or damage to the cylinder walls. By comparing leak down percentages across all cylinders, technicians can diagnose potential problems related to engine performance. This measurement is critical for troubleshooting engine compression issues, which directly affect power output and overall efficiency.

In contrast, measuring fuel efficiency, engine oil temperature, or the condition of the exhaust system doesn't provide information about the sealing integrity of the cylinders, which is the primary purpose of a leak down gauge.