What are the causes and elimination methods for the exhaust pipe white smoke of Cummins diesel engine after starting .

Cummins China Dongfeng Cummins( DCEC),Chongqing(CCEC),Xi’an & Foton Cummins(BFCEC) related technical maintenance and spare parts information as below :

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Exhaust white smoke is caused by the unburned diesel fuel in the combustion chamber after evaporation or cooling water entering the combustion chamber , the causes and elimination methods of white smoke from exhaust of diesel generator set are as follows :

1 . Cylinder liner , cylinder head with cracks or blisters

  • Failure analysis—Cylinder liners ,Cylinder heads with cracks or blisters can cause cooling water to enter the combustion chamber through cracks or blisters , causing the phenomenon of exhausting white smoke , if there are cracks or blisters in the cylinder liner and cylinder head , there will be bubbles to come out in the inlet of the water radiator .


  • Troubleshooting method –After starting the Cummins diesel engine ,use the single –cylinder oil cut method to determine which cylinder is showing white smoke , method are : When a cylinder is disconnected , if the fault phenomenon disappears or weekens , the cylinder head of the suspected shoule be removed for hydraulic pressure test , the hydraulic pressure test method of cylinder liner is basically same as inspection method of the engine body , find the damaged cylinder head or cylinder liner for repair or replacement .
  1. Excessive water content in diesel
  • Failure analysis – The exhaust pipe caused white smoke after the Cummins diesel engines starts ,and it’s cann’t be determined which cylinder is in fault when used the single-cylinder oil cut method for testing ,under the condition of confiming that all parts of Cummins diesel engine work normally ,it can generally be judged that the diesel oil contains excessive water .


  • Troubleshooting method –Remove the oil screw at the bottom of the oil tank , drain the diesel oil with more water inside the oil tank , then remove the diesel flitter for cleaning ,drain the diesel oil with more water content in the  low pressure oil chamber of the fuel injection pump , and then add new diesel oil , the fault can be eliminated .
  1. New engine or overhauled engine
  • Failure analysis—New or overhaul Cummins diesel engine, after use of a period of the time appear to white smoke phenomenon ,this fault is generally caused by the fixing screws looseness of the cylinder head .


  • Troubleshooting method—Remove the cylinder head cover and rocker assembly , and then tighten the cylinder head with fixing screw according to the specified method and torque.
  1. Injector oil pressure is to low , poor atomization or oil simmering
  • Failure analysis—If the fuel injection pressure is too low , the atomizationis poor or there is oil simmering , which will cause the white smoke of the Cummins diesel engine after staring , as the Cummins diesel engine runs longer , the temperature of the body rises ,the phenomenon of smoke white will gradually weaken or disappear . When the Cummins diesel engine loaded , the exhaust pipe will appear smoke white again , This type of failure is common to multi-Cylinder machines .


  • Troubleshooting method—After using the single-cylinder oil break or the pulsation method to determine whihc cylinder is white smoke, remove the injector of the cylinder and then butt on the high-pressure fuel pipe fo the cylinder . Start Cummins diesel engine to idle speed to further check the operation fo the injector, if the fuel injector pressure is too low and atomization is poor or oil simmering , Generally to check the injector’s working condition to repair or replace the injector nozle parts, the fault will be eliminated .
  1. Ambient temperature is too low
  • Failure analysis—When the Cummins diesel engine is started , if the abmient temperature is too low , the engine will be emit white somke after starting ,but as the running time and the temperature of the body increases ,the phenomenon of white smoke will gradually weaken or disapper , this is mainly caused by the individual cylinders are not burning or poor burning .


  • Troubleshooting method—When the above phenomenon accurs after the engine sarts , the operator should increase the speed of the Cummins engine or remove the injector for technical inspection after the oil pressure rises .
  1. The Valves , pistion rings etc. Are not sealed tightly , resluting in air leakage.
  • Failure analysis—The compression pressure is too low in the cylinder causing the exhaust pipe to emit white smoke .


  • Troubleshooting method—Remove the cylinder head and piston connecting rod assembly for inspection ,repair or replace parts with excessive wear parts , clear the carbon deposit inside the combustion chamber , and grind the valve .