Second Chance Garage
All About Car Restoration
Second Chance Garage
All About Car Restoration


SCG Classic Car Troubleshooting Checklist — Troubleshooting Engine Noises — Internal

These are typical noises heard from classic car engines that are not running properly. It is best to listen to internal noises with a stethoscope or hard metal rod placed against the ear and touched to various points on the engine. Always locate the source area of a noise before breaking down an engine.


  1. Low octane fuel
  2. Ignition timing incorrect (early)
  3. Carbon deposits
  4. Air/fuel mixture too lean
  5. Vacuum advance springs weak
  6. Manifold heat control valve stuck closed
  7. Wrong spark plug range
  8. Head gasket protruding into chamber
  9. Valves overheated
  10. Coolant temperature too high (overheating)

Valve Noises

  1. Mechanical clearance too great
  2. Sticking valve
  3. Lifter damaged
  4. Rocker arm face pitted
  5. Weak valve spring
  6. Warped valve stem
  7. Valve seat not concentric with guide
  8. Excessive stem-to-guide clearance
  9. Loose timing gear

Piston Noises

  1. Excessive piston pin clearance
  2. Piston rubbing against cylinder wall
  3. Top end of connecting rod bossing
  4. Collapsed skirt
  5. Piston pin too tight
  6. Tapered cylinder bores
  7. Connecting rod misaligned
  8. Piston hitting ridge at top of cylinder
  9. Carbon accumulation at top of cylinder
  10. Broken ring
  11. Excessive ring side clearance
  12. Ring lands not properly relieved

Rod Noises

  1. Excessive bearing clearance
  2. Low oil pressure
  3. Contaminated oil
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