Hyundai Sonata LF Quiz
Engine Mechanical System

Repair Procedures

In this manual: Engine Mechanical System
General Information — 9Engine Mechanical System — 90Engine Electrical System — 58Emission Control System — 24Engine Control System/Fuel System — 114Drive Shaft and Axle — 15Suspension System — 35Steering — 19Restraints — 50Brake System — 54Body (Interior and Exterior) — 213Body Electrical System — 241Heating, Ventilation, and Air Conditioning — 56DCT (Dual Clutch Transmission) System — 52
10steps
~60min
3/5difficulty
010203040509.87N·mlb·ft
Tightening torque found on this page
Done 0 of 10

Compression Pressure Test
If engine power is insufficient, oil consumption is excessive, or fuel economy is poor, measure the compression pressure.
  1. Make sure the engine oil is of the correct viscosity and at the correct level, and that the battery is fully charged. Operate the vehicle until the engine reaches normal operating temperature. Turn the ignition key to the OFF position.
  2. Remove the engine cover.
  3. Disconnect the injector extension connector (A) and ignition coil connectors (B).
  4. Remove the ignition coils (A).
  5. Remove the spark plugs. Using a 16 mm spark plug socket, remove the 4 spark plugs.
  6. Inspect the compression pressure in the cylinder.
    1. Insert the compression gauge into the spark plug hole.
    2. Set the throttle valve to the fully open position.
    3. While cranking the engine, measure the compression pressure.
      Always use a fully charged battery to obtain an engine speed of 250 rpm or more.
    4. Repeat steps 1) through 3) for each cylinder.
      This measurement must be performed as quickly as possible.
      Compression Pressure Standard: 1225.83 kPa (12.5 kg/cm², 177.79 psi) (200 ~ 250 rpm) Minimum: 1078.73 kPa (11.0 kg/cm², 156.46 psi) Difference between each cylinder: 98 kPa (1.0 kg/cm², 14 psi) or less
    5. If compression is low in one or more cylinders, pour a small amount of engine oil into the cylinder through the spark plug hole, then repeat steps 1) through 3) for the cylinders with low compression.
      A. If adding oil improves compression, the piston rings and/or cylinder bore are likely worn or damaged.
      B. If pressure remains low, a valve may be sticking or seating improperly, or there may be leakage past the head gasket.
  7. Install the spark plugs.

    Tightening torque: 7.8 ~ 9.8 N·m

  8. Install the ignition coil.

    Tightening torque: 9.8 ~ 11.8 N·m

  9. Connect the injector extension connector and the ignition coil connectors.
  10. Install the engine cover.

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