Engine Mechanical: Compression: Inspection

HINT:

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

1. WARM UP AND STOP ENGINE 

   Allow the engine to warm up to normal operating temperature.

2. REMOVE V-BANK COVER AND ENGINE ROOM SIDE COVERS 
3. REMOVE IGNITION COILS 
4. REMOVE SPARK PLUGS 
5. DISCONNECT INJECTOR CONNECTORS 
6. INSPECT 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 clone in as short a time as possible.
      Fig 1: Inserting Compression Gauge Into Spark Plug Hole

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Compression pressure: 

      1,226 kPa (12.5 kgf/cm ²  ,178 psi) or more 

      Minimum pressure: 981 kPa (10.0 kgf/cm ²  ,142 psi) 

      Difference between each cylinder: 

      98 kPa (1.0 kgf/cm ²  ,14 psi) 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 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.
7. RECONNECT INJECTOR CONNECTORS 
8. REINSTALL SPARK PLUGS 
9. RECONNECT IGNITION COIL CONNECTORS 
10. REINSTALL V-BANK COVER AND ENGINE ROOM SIDE COVERS