C6.6 Engines For Caterpillar Built Machines Caterpillar

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

• Coolant temperature sensor circuit

• Low coolant temperature

• Fuel quality

• Valve lash

• Low compression (cylinder pressure)

• Individual malfunctioning cylinder

Recommended Actions

Coolant Temperature Sensor Circuit

1. Connect the electronic service tool to the diagnostic connector.

2. Monitor the display screen on the electronic service tool in order to verify the presence of active diagnostic codes for the coolant temperature. Refer to Troubleshooting, "Engine Temperature Sensor Open or Short Circuit - Test".

3. If the problem has not been eliminated, proceed to "Low Coolant Temperature".

Low Coolant Temperature

1. Check that the water temperature regulator is operating correctly. Refer to Testing and Adjusting, "Water Temperature Regulator - Test".

2. If the water temperature regulator is operating correctly, use the electronic service tool to check the operation of the cooling fan.

3. If the cooling fan is operating correctly, refer to "Fuel Quality".

Fuel Quality

1. Check the diesel fuel for quality. Refer to Testing and Adjusting, "Fuel Quality - Test".

   Note: Diesel fuel with a low cetane value is likely to cause white smoke.

2. If the repair does not eliminate the fault refer to "Valve Lash".

Valve Lash

1. Ensure that the valve lash is correct. Refer to Testing and Adjusting, "Engine Valve Lash - Inspect/Adjust".

2. If the repair does not eliminate the fault proceed to "Low Compression (cylinder pressure)".

Low Compression (cylinder pressure)

1. Perform a compression test. Refer to Testing and Adjusting, "Compression - Test ".

2. If low compression is noted on any cylinders, investigate the cause and rectify the cause.

   Possible causes of low compression are shown in the following list:

   • Loose blanking plugs in the cylinder head.

   • Faulty piston

   • Faulty piston rings

   • Worn cylinder bores

   • Worn valves

   • Faulty cylinder head gasket

   • Damaged cylinder head

3. Perform all necessary repairs.

4. Ensure that the repairs have eliminated the faults.

5. If the repair does not eliminate the fault refer to "Individual Malfunctioning Cylinder".

Individual Malfunctioning Cylinder

1. With the engine speed at a fast idle, use the electronic service tool to isolate one cylinder at a time. Note if there is any reduction in engine speed. If a reduction in engine speed is not noted, the isolated cylinder is not operating under normal conditions. If the isolation of a particular cylinder results in a reduction of engine speed that is less than normal, this may indicate that the cylinder is operating below normal performance. Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.

2. Rectify any faults.