FixVault

Compression Pressure Inspection

WARNING: This page is about a different variant/trim than selected.
NOTE:
  • If there is lack of power, excessive oil consumption or poor fuel economy, measure the compression pressure.
  1. Warm up the engine to the normal operating temperature [80 to - 95°C (176 to - 203°F)].
  2. Disconnect the injector extension connector (A).
    G15555468Courtesy of HYUNDAI MOTOR AMERICA
  3. Remove the LH/RH ignition coils.

    (Refer to Engine Electrical System - "IGNITION COIL ")

  4. Remove the LH/RH spark plugs.

    (Refer to Engine Electrical System - "SPARK PLUG ")

  5. Check the cylinder compression pressure.
    1. Insert a compression gauge into the spark plug hole (A).
      G15555469Courtesy of HYUNDAI MOTOR AMERICA
      NOTE:
      • Always use a fully charged battery to obtain engine speed of 250 rpm or more.
    2. Crank the engine over 7 times to measure compression pressure.
    3. Repeat steps  1 to  2 for each cylinder.
      NOTE:
      • This measurement should be taken as promptly as possible.

      Compression pressure: 

      1, 029 kPa (10.5 kgf/cm2 , 149 psi) (250 - 400 rpm)

      Minimum pressure:  882 kPa (9.0 kgf/cm2 , 128 psi)

      Difference between each cylinder:  98 kPa (1.0 kg/cm2 , 14 psi) or less

    4. If the cylinder compression in 1 or more cylinders is low, pour a small amount of engine oil into the cylinder through the spark plug hole and repeat steps  1 to  3 for cylinders with low compression.
      • If adding oil helps the compression, it is likely that the piston rings and/or cylinder bore are worn or damaged.
      • If pressure stays low, there may be a sticking valve, an improper seating or leakage past the gasket.
      • If the compression pressure is measured low from 2 adjacent cylinders, the cylinder head gasket damage may be suspected.
  6. Reinstall the LH/RH spark plugs.

    (Refer to Engine Electrical System - "SPARK PLUG ")

  7. Install the LH/RH ignition coils.

    (Refer to Engine Electrical System - "IGNITION COIL ")

  8. Install the injector extension connector (A).
    G15555470Courtesy of HYUNDAI MOTOR AMERICA