How To Test Engine Compression

A compression test is a basic part of a routine tune up for an air cooled Volkswagen engine. With these instructions you can check the engine compression yourself.

Compression is a measurement of the pressure that builds up within a cylinder as the piston rises and both valves are closed. For the fuel mixture to burn properly a certain range of pressure is required.

The two main factors that affect compression are the condition of the piston rings and the valves. Obviously, the valves need to be fully closed on the compression stroke to avoid loss of pressure.

Before you check the compression the engine needs to be at normal operating temperatures. Let your Volkswagen idle until the engine is completely warmed up.…

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