Operation CHARM: Car repair manuals for everyone.

Compression Check: Testing and Inspection

1. Ensure oil is of proper viscosity and level is satisfactory.
2. Ensure battery is fully charged, then start and warm engine to normal operating temperature.
3. Turn ignition Off, then remove all spark plugs.
4. Ensure throttle plates are in wide open position, then install a remote starter switch to starter circuit.
5. Install compression gauge and crank engine at least five times, record highest compression reading.
6. Repeat step 5 for each cylinder.
7. If lowest reading is within 75 percent of highest reading, compression pressure is satisfactory.