Cylinder Compression Pressure Test

DIAGNOSIS AND TESTING - CYLINDER COMPRESSION PRESSURE
The results of a cylinder compression pressure test can be utilized to diagnose several engine malfunctions.

Ensure batteries are completely charged and the engine starter motor is in good operating condition. Otherwise, the indicated compression pressures may not be valid for diagnostic purposes.

1. Disconnect the fuel inlet line to the fuel transfer pump. Plug the fuel line from the fuel tank.
2. Start the engine and idle until the engine stalls (runs out of fuel).
3. Disconnect all three injector wire harness connectors at the rocker housing.
4. Remove the breather cover and cylinder head cover.
5. Remove the high pressure fuel line between the cylinder head and fuel rail for the cylinder to be tested.
6. Remove the exhaust rocker lever.
7. Use Tool 9010 to remove the injector and copper sealing washer.
8. Install the exhaust rocker lever and torque to 43 Nm (32 ft. lbs.).
9. Cover the remaining rocker levers with clean shop towels to prevent any oil splatter under the hood.
10. Place a rag over the compression test tool fitting. Crank the engine for 2-3 seconds to purge any fuel that may have drained into the cylinder when the injector was removed.
11. Connect the compression test gauge.
12. Crank the engine for 5 seconds and record the pressure reading. Repeat this step three times and calculate the average of the three readings.
13. Combustion pressure leakage can be checked if cylinder pressure is below the specification. Perform the leakage test procedure on each cylinder according to the tester manufacturer instructions.
14. Upon completion of the test check an erase any engine related fault codes.