To determine whether pressure's escaping from the engine, you need to check the compression in the cylinders. For this job, you need a compression gauge (see Figure 8-9).

Periodic tests are the best indicators of total cylinder sealing and efficient operation A remote starter switch and a top-quality, screw-in-type compression gaugeâ such as these models from ...

We take a close look at what engine compression means, what it does, and how to test it.

But without verifying the combustion chamber volume on the cylinder heads, it's impossible to be sure of the engine's true compression.

When you bring your vehicle in for a compression test, a mechanic places a gauge into each of the cylinders to read how much pressure the engine is producing when the engine turns over.