3406C Truck Engine Caterpillar

Note: Troubleshoot a performance problem first if excessive exhaust smoke is present. Refer to Troubleshooting, "Low Power" or Troubleshooting, "Engine Misfires, Runs Rough Or Is Unstable".

Probable Causes

• Faulty Automatic Timing Advance Unit

• Fuel Ratio Control setting

• Fuel injection timing

• Faulty fuel injection nozzle

• Air inlet restriction or air inlet leak

• Exhaust restriction or exhaust leak

• Faulty turbocharger

Recommended Repairs

Faulty Automatic Timing Advance Unit

Check the automatic timing advance unit for proper operation. Refer to Systems Operation, Testing and Adjusting, "3406C Diesel Truck Engine".

Fuel Ratio Control Setting

If excessive black smoke appears during acceleration only, check the Fuel Ratio Control setting. If the Fuel Ratio Control is adjusted too rich, black smoke during acceleration can occur. Refer to Troubleshooting, "Fuel Ratio Control".

Incorrect Fuel Injection Timing

Check the fuel injection timing. Ensure that the fuel injection timing is adjusted correctly. Refer to the Systems Operation, Testing And Adjusting, "3406C Diesel Truck Engine".

Faulty Fuel Injector Nozzle

Faulty fuel injection nozzles can cause the engine to misfire, which will cause the engine to run rough. Faulty fuel injection nozzles can also cause too much smoke even if the engine is running smoothly. Check the fuel injection nozzles. Refer to Special Instruction, SEHS7292 for additional information.

Air Inlet Restriction or Air Inlet Leak

Check the air inlet for restrictions. Also check the air inlet for air leaks.

Exhaust Restriction or Exhaust Leak

Check the exhaust system for restrictions. Also check the exhaust system for exhaust leaks.

Faulty Turbocharger

Check the inlet manifold and the exhaust manifold for oil. If oil is present in the inlet manifold or the exhaust manifold, repair the turbocharger or replace the turbocharger.