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Home >> Hyundai >> 2019 >> Accent SE, Automatic Trans >> Repair and Diagnosis >> Engine Mechanical >> Mechanical >> Engine Mechanical System - General Information >> Repair Procedures >> Compression Pressure Inspection

Compression Pressure Inspection

NOTE:
  • If the there is lack of power, excessive oil consumption or poor fuel economy, measure the compression pressure.
  1. Make sure the oil in the crankcase is of the correct viscosity and at the correct level and that the battery is correctly charged. Operate the vehicle until the engine is at normal operating temperature. Turn the ignition switch to the OFF position.
  2. Remove the engine cover.

    (Refer to Engine And Transaxle Assembly - "ENGINE COVER ")

  3. Disconnect the injector extension connector (A) and the ignition coil connectors (B).
    G12594100Courtesy of HYUNDAI MOTOR AMERICA
  4. Remove the ignition coils.

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

  5. Remove the spark plugs.

    Using a 16mm plug wrench, remove the 4 spark plugs.

    (Refer to Engine Electrical System - "Spark Plug REPAIR PROCEDURES ")

  6. Check the cylinder compression pressure.
    1. Insert a compression gauge into the spark plug hole.
      G12594101Courtesy of HYUNDAI MOTOR AMERICA
    2. Set the throttle plate in the wide-open position.
    3. While cranking the engine, measure the compression pressure.
      NOTE:
      • Always use a fully charged battery to obtain engine speed of 250 RPM or more.
    4. Repeat step  1) through  3) for each cylinder.
      NOTE:
      • This measurement must be done in as short time as possible.

      Compression pressure 

      Standard: 1225.83kPa (12.5kg/cm2, 177.79psi) (200-250 RPM)

      Minimum: 1078.73kPa (11.0kg/cm2, 156.46psi)

      Difference between each cylinder:

      98kPa (1.0kg/cm2, 14psi) or less

    5. If the cylinder compression in one or more cylinders is low, pour a small amount of engine oil into the cylinder through the spark plug hole and repeat step  1) through  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, a valve may be sticking or seating is improper, or there may be leakage past the gasket.
  7. Install the spark plugs.

    (Refer to Engine Electrical System - "Spark Plug REPAIR PROCEDURES ")

  8. Install the ignition coils.

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

  9. Connect the injector extension connector (A) and the ignition coil connectors (B).
    G12594102Courtesy of HYUNDAI MOTOR AMERICA
  10. Install the engine cover.

    (Refer to Engine And Transaxle Assembly - "ENGINE COVER ")

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