What action is taken after installing the gauge adapter for a compression test?

After installing the gauge adapter for a compression test, it is essential to rotate the engine until the gauge stops rising. This action allows you to accurately measure the maximum compression pressure generated within the cylinder during the engine's compression stroke. By continuing to rotate the engine, typically through the use of the starter or a manual crank, you ensure that the gauge receives the highest possible pressure reading, which reflects the engine's health and efficiency.

This step is crucial because a compression test is performed to assess the sealing capability of the engine's valves, piston rings, and head gasket. Accurate readings are necessary for diagnosing potential issues, so ensuring the gauge has stabilized at its highest reading is a vital part of the testing process.

Other options, such as starting the engine immediately, would not be appropriate since the purpose of a compression test is to evaluate compression without the interference of an operating engine. Removing the spark plug is typically performed before installing the gauge to prevent damaging the engine and ensure safety, but it is not a direct action following the installation. Checking the fuel level is unrelated to the process of measuring compression, as it pertains more to the fuel system rather than the compression test itself.