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Home >> Subaru >> 2019 >> Outback 2.5i >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Mechanical System (3.6L)) >> Compression >> Inspection
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Section 12 (Engine Mechanical System (3.6L)): Compression: Inspection

WARNING: This page is about a different variant/trim than selected.
CAUTION: After warming-up, engine becomes very hot. Be careful not to burn yourself during measurement.
NOTE:
  • Before checking the compression pressure, the compression condition of each cylinder can be confirmed as a guide by using the compression measurement mode in Subaru Select Monitor. Ref. to ENGINE (DIAGNOSTICS) (H6DO)>ACTIVE TEST>OPERATION .
  • In the compression measurement mode, the compression condition is judged by each cylinder speed. The high speed cylinder has low compression pressure and low speed cylinder has high compression pressure.
  1. Remove the collector cover.
    1. Carefully pull up the rear of collector cover at two positions (A).
    2. Carefully pull up the front of collector cover at two positions (B) while moving it forward.
      G11585612Courtesy of SUBARU OF AMERICA, INC.
  2. After warming-up the engine, turn the ignition switch to OFF.
  3. Make sure that the battery is fully charged.
  4. Check the starter motor for satisfactory performance and operation.
  5. Remove the fuse of fuel pump from main fuse box.
    G10262219Courtesy of SUBARU OF AMERICA, INC.
  6. Start the engine and run it until it stalls.
  7. After the engine stalls, crank it for five more seconds.
  8. Turn the ignition switch to OFF.
  9. Remove all spark plugs. Ref. to IGNITION (H6DO)>SPARK PLUG>REMOVAL .
  10. Install the battery. Ref. to STARTING/CHARGING SYSTEMS (H6DO)>BATTERY>INSTALLATION>BATTERY .
  11. Install the compression gauge to the spark plug hole.
    NOTE: When using a screw-in type compression gauge, the screw should be less than 18 mm (0.71 in) long.
    G10262495Courtesy of SUBARU OF AMERICA, INC.
  12. Depress the accelerator pedal to full throttle.
  13. Crank the engine by the starter motor, and read the maximum value on the gauge when the needle of gauge is steady.
    NOTE:
    • Perform at least two measurements per cylinder, and make sure that the values are correct.
    • If the compression pressure is out of standard, check or adjust the pistons, valves and cylinders.

    Compression pressure: 

    At 350 r/min 

    Standard 

    1, 128 - 1, 471 kPa (11.5 - 15.0 kg/cm2 , 164 - 213 psi)

    Difference between cylinders 

    49 kPa (0.5 kg/cm2 , 7 psi) or less

  14. After inspection, install the related parts in the reverse order of removal.
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