CP7821 is a compression tester that is used to test the compression of a car engine.
This document provides step-by-step instructions for operating the Actron CP7821 Compression Tester. It details the preparation required before testing, such as ensuring the engine is at normal operating temperature and removing spark plugs. The guide explains how to perform the compression test on each cylinder and interpret the results.
Crank the engine for at least 4 compression strokes or until pressure stops rising.
If the needle fails to advance normally, remains the same for several strokes, then starts to climb.
A compression reading that is 15 pounds or more above the manufacturer's specification.
A reading on two adjacent cylinders that is 20 pounds or more lower than the rest.