How can a simple test for compression be conducted?

A simple test for compression can be effectively conducted by removing the spark plugs one at a time and placing a finger or thumb over the spark plug hole to feel for compression pressure as the engine is turned over. When a cylinder has adequate compression, the pressure will force the air out of the hole, which can be felt with your finger. This is a basic method to assess whether each cylinder is generating enough compression to create effective combustion.

When the engine is cranked, if the cylinder has good compression, the pressure buildup will create a strong enough force to push against your finger, indicating that the piston is sealing properly against the cylinder walls and that the valves are functioning correctly. This method is practical for quickly diagnosing potential issues related to engine compression without needing specialized tools.

The other methods listed would not effectively indicate engine compression. Measuring exhaust gases provides insight into engine performance and combustion efficiency but does not directly gauge cylinder compression. Checking the fuel level pertains to fuel delivery rather than compression. Listening to engine sounds can suggest various issues within the engine, but auditory assessment does not provide a reliable measure of compression.