3176C, 3406E and 3456 Industrial Engines Troubleshooting – Exhaust Has Excessive White Smoke

Note: Some white smoke may be present during cold start-up conditions when the engine is operating normally. If the white smoke persists, there may be a problem.

Probable Causes

Cold mode


  • Cold mode operation 

Starting Aids


  • Jacket water heater 
  • Air inlet heater 
  • Ether injection 



  • Coolant temperature 
  • Coolant leak 

Engine Speed/Timing


  • Engine speed/timing sensor 

Electronic Control Module (ECM)


  • Flash file 



  • Injector 



  • Fuel supply 

Low Compression


  • Component wear 

Recommended Actions

Cold Mode Operation

Excessive white smoke emissions may occur during cold mode operation of the engine. During cold mode operation of the engine, the ECM may modify the injection timing and the ECM may cut out certain engine cylinders. This will increase startability and this will reduce warm up time. Cold mode is activated whenever the engine coolant temperature falls below a predetermined value. Cold mode remains active until the engine has warmed or a time limit is exceeded.

Jacket Water Heater

If the application has a jacket water heater that is installed, check for proper operation of the circuit. Repair the circuit for the jacket water heater, if necessary.

Air Inlet Heater

If the application has an air inlet heater that is installed, ensure that the heater is operating correctly. Refer to the particular test procedure for your application.

Ether Injection

If the application has an ether injection system, ensure that the ether canister is not empty or low. Replace the ether canister if the ether canister is empty or low. If an electrical problem with the ether injection system is suspected, refer to the particular test procedure for your application.

Coolant Temperature

Compare the coolant temperature from Caterpillar Electronic Technician (ET) to the coolant temperature that is obtained from the 6V-9130 Temperature Adapter (MULTIMETER). Ensure that the temperature readings are reasonable for the conditions that are present.

Coolant Leak

Check for an internal coolant leak into the cylinder and/or the exhaust.

Engine Speed/Timing Sensor


  1. Check the calibration of the engine speed/timing sensor(s). Refer to Troubleshooting, “Timing – Calibrate”.


  1. Verify that the timing of the crankshaft and camshaft drive gears are set with the proper orientation. Refer to Disassembly and Assembly for information that is related to the correct gear installation.

Flash File

Verify that the correct flash file is installed in the ECM. Refer to Troubleshooting, “ECM Software – Install”.



  1. Perform the “Cylinder Cutout Test” on Cat ET in order to try to isolate any cylinders that may be misfiring. A misfiring cylinder could be related to an injector that is worn or in poor repair. Refer to Troubleshooting, “Injector Solenoid – Test”.


  1. Cut out each individual cylinder for 30 to 60 seconds. Verify that the smoke decreases.


  1. If Cat ET indicates a problem, remove the electronic unit injector from the suspect cylinder. Refer to Disassembly and Assembly.

Fuel Supply

Check the fuel quality. Low cetane fuel can create white smoke. If necessary, replace the fuel with a higher cetane fuel.

Component Wear


  1. Check the valve lash and reset the valve lash, if necessary. Refer to Systems Operation/Testing and Adjusting.


  1. Possible causes of low compression are shown in the following list: 
    • Faulty piston 
    • Faulty piston rings 
    • Worn cylinder bores 
    • Worn valves 
    • Faulty cylinder head gasket 
    • Damaged cylinder head 


  1. Perform all necessary repairs. Ensure that the repairs have eliminated the problem.

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