Abnormal engine noise

1. Knocking
   

• IC Igniter trouble.
  

  
  

   

• Carbon built up in combustion chamber.
  

  
  

• Fuel poor quality.
  

  
  

   

   

   

   

• Spark plug incorrect.
  

  
  

   

1. Overheating piston slap
   

• Cylinder piston clearance excessive.
  

  
  

   

• Cylinder piston worn.
  

  
  

   

   

   

   

   

   

   

• Connecting rod bent.
  

  
  

   

• Piston pin, piston holes worn.
  

  
  

   

1. Other noise
   

• Connecting rod small end clearance excessive.
  

  
  

   

   

   

   

   

   

   

• 
  Connecting rod big end clearance excessive.
  

  
  

   

• Piston ring worn.
  

  
  

   

• Piston seizer, damage.
  

  
  

   

• Cylinder head gasket leaking.
  

  
  

   

• Exhaust pipe leaking at cylinder head connection.
  

  
  

   

• Crank shaft run out excessive.
  

  
  

   

• Engine mounts loose.
  

  
  

• Crankshaft bearing worn
  

  
  

   

   

   

   

• Camshaft chain, sprocket, guide worn.