Posted on 2/27/2026
Engines can feel a little off in ways that are hard to describe. Maybe it starts fine, but feels weak on hills, or it idles a bit rough and never quite smooths out. Sometimes the check engine light shows up and the car still drives, just not like it used to. When symptoms suggest an engine that may not be sealing and building pressure as it should, a compression test is one of the clearest ways to assess the engine’s mechanical health. It gives you a yes or no direction before you spend money chasing the wrong thing. Engine Compression Test Basics Compression is the pressure an engine builds inside each cylinder when the piston comes up on the compression stroke. Good compression means the cylinder is sealing well, which supports power, a smooth idle, and efficient combustion. Low compression means the cylinder is leaking pressure somewhere, and that leak changes how the engine runs. This test is most helpful when you want to separate engine wear from bolt-o ... read more