How can you tell if your engine has lost compression?

You can check for lost compression in your engine by conducting a compression test, which measures the pressure in each cylinder. If one or more cylinders show significantly lower readings than the others, it indicates a compression loss. Additionally, symptoms like rough idling, reduced power, excessive exhaust smoke, or unusual noises can also suggest compression issues. Finally, a leak-down test can help pinpoint the source of the compression loss.