LEAK-DOWN TESTING

Determining the mechanical condition of an engine can be a tricky proposition. With the right diagnostic tools, you can zero in on problem areas that are the most important.

Let’s say that you have a trusty engine that has been in operation for a few years. All of a sudden the running becomes rough and unpredictable. You’ve done all the routine service items like tune up, valve adjustment, and even cleaning up the carbs, but it’s still running rough. What’s next?

The most traditional engine test would be a compression test. This test is a dynamic test that involves turning the motor over with the starter motor. With the spark plugs removed, a hollow spark plug replacement with a hose attached is connected to a gauge. These gauges are