Check Compression

Check compression1.064

  1. Remove wire from fuel shut-off solenoid and insulate the wire.
  2. Clean connections on injector lines.
  3. Remove injector lines (be sure that delivery valves are not loosened when loosening injector lines on injection pump.).
  4. Remove injectors using deep well socket and store in clean area.
  5. Remove all heat shields except #1 cylinder.   Caution: loose heat shields can be blown out during compression check.
  6. Install adapter on #1 cylinder.
  7. Install diesel compression test gauge onto adapter.
  8. Operate starter until gauge reads highest reading.
    • 28-34 bar (400 – 500 psi)
    • maximum cylinder variation  5 bar (71 psi)
  9. Release pressure
  10. Repeat process on remaining cylinders.
    • Low readings on adjacent cylinders gasket = leakage between cylinders.
    • Low readings on one cylinder = valve leakage.
    • Low readings on all cylinders = worn pistion rings or jumped valve timing
  11. A low reading can be rechecked by adding 1 tablespoon of engine oil through the injector hole:
    1. If the compression readings increase slightly this indicates valve leakage.
    2. If the compression readings increase significantly this indicates worn piston rings.
    3. If compression does not increase, check valve timing.

Always install new heat shields before reinstalling injectors.