A compression test is to determine how much pressure the engine makes, and a leakdown test measures its ability to hold pressure. See All 14 Photos Engine CompressionAtmospheric pressure at sea ...

A compression test reveals the condition of your engine's valves, its valve seats, and piston rings and whether these parts are wearing evenly. Healthy engines should have compression over 100 psi ...

Compression test kits do just what they say: measure the ability of each cylinder of your engine to combust the fuel/air mixture without losing any of the resulting energy. While they're not as ...