Cylinder Compression Pressure Test

DIAGNOSIS AND TESTING - CYLINDER COMPRESSION/LEAKAGE TESTS

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 filter housing. Plug the fuel line from the fuel tank.

NOTE: Failure to plug fuel line will result in fuel leak.

2. Remove fuel transfer pump relay from PDC.
3. Start the engine and idle until the engine stalls (runs out of fuel).
4. FOR EARLY BUILDS Disconnect all three injector wire harness connectors at the rocker housing. FOR LATE BUILDS Remove the cylinder head cover.
5. FOR LATE BUILDS Remove the cylinder head cover carrier gasket.
6. FOR EARLY BUILDS Remove the breather cover and cylinder head cover.
7. Remove the high pressure fuel line between the cylinder head and fuel rail for the cylinder to be tested. Use tool#9011 to cap this fuel rail on the cylinder being tested.
8. Remove the fuel connector tube nut and fuel connector tube.
9. Remove the exhaust rocker lever.
10. Use Tool 9010 to remove the injector and copper sealing washer.
11. Install the exhaust rocker lever and torque to 36 Nm (27 ft. lbs.).
12. Cover the remaining rocker levers with clean shop towels to prevent any oil splatter under the hood.
13. 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.
14. Connect the compression test gauge.
15. Crank the engine for 5 seconds and record the pressure reading. Repeat this step three times and calculate the average of the three readings.

NOTE: The minimum cylinder pressure is 350 psi. Cylinder pressure should be within 20% from cylinder to cylinder.

16. 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. Cylinder Leak Down Test
17. Upon completion of the test check and erase any engine related fault codes.