Troubleshooting Cummins Diesel Engines

Troubleshooting Procedures and Techniques

 This guide describes some typical engine operating problems, their causes, and some acceptable corrections to those problems. Unless noted otherwise, the problems listed are those which an operator can diagnose and repair.  See an Authorized Repair Location for diagnosis and repair of problems not listed.

Follow the suggestions below to develop good troubleshooting procedures:  

• Study the problem thoroughly before acting.
• Do the easiest and obvious things first.
• Find and correct the basic cause of the problem.  

 Troubleshooting Symptoms

 Use the charts given on the following pages to help find the cause and correction of a malfunction. Read each row of blocks from top to bottom. Follow the arrows through the chart to identify corrective action.

• Lubricating Oil Pressure Low
• Lubricating Oil Pressure Too High 
• Lubricating Oil Loss
• Coolant Temperature Above Normal 
• Coolant Loss
• Coolant Temperature Below Normal
• Coolant Contaminated
• Lubricating Oil Contaminated 
• Fuel or Oil Leaking from Exhaust Manifold 
• Exhaust Smoke Excessive Under Load
• Engine Will Not Reach Rated Speed When Loaded
• Power Output Low
• Engine Misfiring 
• Fuel Knock 
• Fuel Consumption Excessive  
• Vibration Excessive
• Engine Noises Excessive
• Alternator Not Charging or Insufficient Charging  
• White Smoke Excessive During Cold Start 

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• Engine Will Not Crank or Cranks Slowly
• Engine Hard to Start or Will Not Start (Exhaust Smoke Present)
• Engine Cranks But Will Not Start (No Smoke From Exhaust)
• Engine Starts But Will Not Keep Running
• Engine Will Not Shut Off
• Rough Idle, Warm Engine
• Engine Surges at Idle

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