If an engine fails to build compression on the first stroke but improves on subsequent strokes, what should be performed next?

When an engine fails to build compression on the first stroke but shows improvement on subsequent strokes, a wet compression test is the most appropriate next step. This test involves adding a small amount of oil to the combustion chamber before conducting another compression test. If the compression increases significantly, it indicates that the issue may be related to worn piston rings or cylinder walls, as the oil helps to create a temporary seal, suggesting that the compression loss might be due to wear rather than a more serious issue like a blown head gasket.

The rationale for this approach is based on an understanding of engine mechanics and how compression is affected by various components. A wet compression test can provide insight into whether the compression issue is due to internal engine wear or other factors. If the compression remains low after the wet test, it would suggest that there might be a major internal issue such as a leaking head gasket or valve seating problem.

While performing a compression leak test or a visual inspection of the valves might seem reasonable as well, they do not provide the specific information about the condition of the rings and cylinders that a wet compression test does. Replacing fuel injectors would be unrelated to compression issues, as injectors affect fuel delivery rather than compression itself. Thus, the wet compression test is the