Section 254 (Engine Mechanical): Compression: Inspection

HINT:

If there is lack of power, excessive oil consumption or poor fuel economy, measure the compression pressure.

1. REMOVE OUTER COWL TOP PANEL (See  REMOVAL  ) 
2. WARM UP AND STOP ENGINE 

   Allow the engine to warm up to normal operating temperature.

   Fig 1: Inserting A Compression Gauge Into Spark Plug Hole

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. REMOVE IGNITION COILS (See  IGNITION  ) 
4. REMOVE SPARK PLUGS 

   Using a 16 mm plug wrench, remove the 6 spark plugs.

5. CHECK CYLINDER COMPRESSION PRESSURE 
   1. Insert a compression gauge into the spark plug hole.
   2. Fully open the throttle.
   3. While cranking the engine, measure the compression pressure.

      HINT:

      Always use a fully charged battery to obtain engine speed of 250 RPM or more.

   4. Repeat steps (a) through (c) for each cylinder.
      NOTE: This measurement must be done in as short a time as possible.
      • Compression pressure: 1,500 kPa (15.3 kgf/cm ²  , 218 psi) 
      • Minimum pressure: 1,000 kPa (10.2 kgf/cm ²  , 145 psi) 
      • Difference between each cylinder: 100 kPa (1.0 kgf/cm ²  , 15 psi) or less 
   5. 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 (a) through (c) 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.
6. REINSTALL SPARK PLUGS 
7. REINSTALL IGNITION COILS (See  IGNITION  ) 
8. REINSTALL OUTER COWL TOP PANEL (See  INSTALLATION  )