How to Use a Compression Gauge

The more an engine is used, the greater the wear on the engine's internal components. An engine produces its power within the combustion chambers. As the internal components wear out, the power that the engine produces and the efficiency at which it produces that power decline. Thankfully, this wear is gradual. If the symptoms of internal engine wear can be discovered at an early stage, steps can be taken to prepare for a future repair. A compression gauge is an instrument used to determine the condition of the engine's parts within the combustion chamber without having to disassemble the engine.

Things You'll Need

• Socket wrench Vehicle's specification manual

Instructions

1. Remove all of the engine's spark plugs with a socket wrench.

2. Screw the end of the compression gauge into one of the spark plug holes.

3. Block the throttle wide open, either under the hood at the fuel delivery system or with the accelerator pedal fully depressed.

4. Activate the ignition with the ignition key, and let the engine crank several times to obtain the maximum reading on the compression gauge. Record this reading, then repeat the above steps for all remaining cylinders.

5. Compare the readings to the compression limits in your vehicle's specifications manual. If the readings fall within the limits on all cylinders, there is no compression problems. If the gauge is reading extremely low on all cylinders, this is an indication of damaged pistons or piston rings. If the gauge reads low on two adjacent cylinders only, this is an indication of a faulty head gasket.