Compression Test


  1. If plugs do not have anti-seize coated threads, then with engine cold, loosen plugs and coat threads with anti-seize, and tighten snug.
  2. If plugs have anti-seize, then with engine cold. crack plugs and tighten snug.
  3. Take car for a 5 minute drive to get engine temperature to middle of gauge.
  4. Pull parking brake and put car in neutral.
  5. Block front wheels.
  6. Remove all plugs (read each plug and record date, plug location and plug condition in a journal)
  7. Connect compression tool to cylinder 1.
  8. Disconnect ignition cable from starter solenoid.
  9. Connect remote starter to solenoid first THEN to battery +POS terminal.
  10. Double check that car is in neutral.
  11. Reset Compressor
  12. Hold throttle linkage open.
  13. Press and hold remote starter for "5 Mississippi's"
  14. Record date, value on compression tester, and associated plug in journal.
  15. Repeat for all cylinders.
  16. Disconnect remote starter at +POS terminal first then at starter solenoid.
  17. Reconnect ignition cable to starter solenoid.
  18. Clean and re-gap plugs.
  19. Coat plugs with anti-seize.
  20. After the engine cools, reinstall plugs to proper torque. (11-14ft-lbs) 


Analyzing Compression Test Data:


Improving Compression Results


If you feel spanky.... repeating a compression tests on a cylinder but adding a few teaspoons or squirts of motor oil in the plug hole prior to the measurement will tell you if the rings are bad. The oil acts to create a better seal around the rings. If the compression results improve then the rings are worn. If the compression remains low then the valves are not sealing or the head gasket has a problem.

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