FixVault
Home › Nissan-Datsun › 2004 › Sentra SE-R › Repair and Diagnosis › External Pages › Different car › Section 1469 (Engine Mechanical) › Cylinder Head › On-Vehicle Service › Checking Compression Pressure

Checking Compression Pressure

WARNING: This page is about a different car, the 2005 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
  1. Run the engine until it reaches normal operating temperature.
  2. Turn the ignition switch to OFF.
  3. Release fuel pressure and leave the fuel pump electrically disconnected. Refer to FUEL PRESSURE RELEASE .
  4. Remove all six spark plugs. Refer to REMOVAL AND INSTALLATION . ,
  5. Attach a compression tester to No. 1 cylinder.
  6. Depress accelerator pedal fully to keep the electric throttle control actuator butterfly-valve wide open to maximize air intake flow.
  7. Crank the engine and record the highest gauge indication.
  8. Repeat the measurement on each cylinder (steps 5 - 7).
    NOTE: Always use a fully-charged battery to obtain specified engine speed.

    Unit: kPa (kg/cm2 , psi)/300 RPM

    Fig 1: Identifying Appropriate Compression Tester
    G02475042Courtesy of NISSAN MOTOR CO., U.S.A.
    COMPRESSION PRESSURE SPECIFICATION

    Unit: kPa (kg/cm2 , psi)/300 RPM
    Standard Minimum Difference limit between cylinders
    1, 275 (13.0, 185) 981 (10.0, 142) 98 (1.0, 14)
  9. If compression in one or more cylinders is low:
    1. Pour a small amount of engine oil into cylinders through the spark plug holes.
    2. Retest compression (steps 5 - 8).
      • If adding oil helps raise compression pressure, then the piston rings may be worn or damaged. If so, replace piston rings after checking piston.
      • If the pressure stays low, a valve may be sticking or is seating improperly. Inspect and repair the valve and/or valve seat. Refer to VALVE . If the valve and/or valve seat is damaged excessively, replace as necessary.
      • If compression stays low in two or more cylinders that are next to each other:
        • The cylinder head gasket may be leaking.
        • Both cylinders may have valve component damage. Inspect and repair as necessary.
  10. After inspection is complete, install removed components.
  11. Start engine and confirm that engine runs smoothly.
  12. Perform trouble diagnosis. If DTC appears, erase it. Refer to TROUBLE DIAGNOSIS .
About FixVault