What is the main purpose of a cylinder leakage tester?

The main purpose of a cylinder leakage tester is to diagnose valve sealing efficiency. This tool helps to determine how well the valves are sealing within the combustion chamber. When performing a cylinder leakage test, compressed air is introduced into the cylinder through the spark plug hole. If the valves do not seal properly, air will escape past the valves. This escaping air can be heard from the intake or exhaust manifolds or can be seen bubbling through coolant if the head gasket is leaking. Identifying valve sealing efficiency is crucial because poor sealing can result in reduced engine performance, loss of compression, and increased emissions.

While there are other tools and methods to assess various components of the engine, such as fuel injectors, exhaust systems, or fuel pressures, the cylinder leakage tester specifically focuses on the internal sealing of the cylinder, particularly concerning the valves, making it uniquely suited for this purpose.