A. White Smoke (Go to Step 1)
Probable Cause(s):
* Cold Outside Temperature
* Long Idle Periods
* Low Quality Fuel
* Air In Fuel System
* Water In Fuel System
* Fuel Pressure Is Low
* Air Inlet Heater (if equipped) Not Operating Properly
* Valve Adjustment Not Correct
* Misfiring Cylinder(s)
* Intake/Exhaust Valves Or Piston Rings Leak Compression
* Defective Unit Injector(s)
* Defect In Intake Manifold Air Temperature Sensor
* Defect In Coolant Temperature Sensor
B. Black Smoke (Go to Step 17)
Probable Cause(s):
* Defective Unit Injector(s)
* Restrictions And/Or Leaks In Air Inlet System
* Exhaust System Restriction
* Defective Turbocharger
C. Blue Smoke (Go to Step 21)
Probable Cause(s):
* Oil Level In Engine Too High
* Failure Of Turbocharger Oil Seal
* Worn Or Broken Valve Guides
* Worn Piston Rings And/Or Cylinder Wall(s)
* Wear Or Damage To Pistons
1. Cold outside temperatures:
When the air outside is cold, the cylinder temperature is cooler. Not all the fuel will burn in the cylinders. The fuel which does not burn comes out the exhaust as white smoke. White smoke is normal in cold temperatures until the engine operates long enough to become warm. There will be less white smoke if No. 1 diesel fuel is used.
The inlet air heater is used to improve the cold start capability of the engine and to reduce white smoke after startup. The ECM controls the inlet air heater grid and indicator lamp (on truck dash) through the inlet air heater relay. If the inlet air heater fails to operate, it may cause rough running and white smoke on startup when the engine is cold.
2. Long idle periods:
When an engine runs at idle speed for a long period of time, the cylinders cool and all of the fuel does not burn. Do not idle an engine for a long period of time. Stop an engine when it is not in use. If long idle periods are necessary, use No. 1 diesel fuel.
3. Low quality fuel:
Test the engine using fuel according to recommendations by Caterpillar Inc. Refer to Truck Performance And Driveability Diagnostic Guide, LEBT3477.
4. Air in fuel system:
With air in the fuel system the engine will normally be difficult to start, run rough and release a large amount of white smoke. Find the air leak in the fuel system and correct it. If air is in the system, it will generally get in on the suction side of the fuel transfer pump. Refer to Problem 34: Air In Fuel.
5. Water in fuel system:
Water in the fuel system can result in misfiring. Check injection sleeve or head gasket for water leak.
6. Fuel pressure is low:
Make sure there is fuel in the fuel tank. Look for leaks or bad bends in the fuel line between fuel tank and fuel transfer pump. Look for air in the fuel system. (If fuel in the fuel tank cannot be checked for air, install a sight tube in the fuel line). Make sure the fuel filters are clean, then check fuel pressure. The outlet pressure of the fuel transfer pump must be 400 to 525 kPa (58 to 76 psi) at full load speed measured at the inlet to the secondary filter. If fuel pressure is lower than the above pressure, check the fuel transfer pump and fuel pressure regulating orifice at the fuel return line.
7. Air Inlet Heater (if equipped) Not Operating Properly:
Refer to Problem 32: Air Inlet Heater (If Equipped) in the Troubleshooting Section of the Service Manual.
8. Valve adjustment not correct:
Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.
9. Misfiring cylinder(s):
Refer to Problem 4: Engine Misfiring Or Running Rough.
10. Intake/exhaust valves or piston rings leak compression:
a. Check intake/exhaust valves for low compression. Repair or replace as necessary.
b. Worn piston rings and/or cylinder walls can be the cause a loss of compression. This condition can cause more than the normal amount of fumes (blow-by) coming from the crankcase breather. The 8T2700 Indicator Group is used to check the amount of blow-by. The test procedure is in Special Instruction, SEHS8712. If necessary make a visual inspection of the cylinder walls and piston rings. Measure the cylinder walls and piston rings. For the cylinder and piston ring specifications see the Specification Section of the Service Manual. Repair and replace parts as necessary.
11. Defective unit injector(s):
Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Injector Solenoid Test.
12. Defect in intake manifold air temperature sensor:
Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Engine Sensor Open or Short Circuit Test.
13. Defect in coolant temperature sensor:
Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Engine Sensor Open or Short Circuit Test.
Black Smoke
Probable Cause(s):
14. Defective unit injector(s):
Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Injector Solenoid Test.
15. Restrictions and/or leaks in air inlet system:
a. Check for leaks.
b. Check the pressure in the air inlet manifold. Check pressure in the air inlet manifold. Look for restrictions at the air cleaner. Check the ATAAC for cracks.
c. Look for restrictions in the air cleaner.
d. Defect in the air-to-air aftercooler. Check temperature of inlet and outlet air from air cooler. Remove any external or internal restrictions.
16. Exhaust System Restriction:
Make a visual inspection of the air inlet system and check for damage to piping or a defective muffler. If no damage is found, check the system by checking the back pressure from the exhaust (pressure difference measurement between exhaust outlet and atmosphere). The back pressure must not be more than 1016 mm (40 in) of water. If a gauge is not available, check by removing the exhaust pipes from the exhaust manifold. With the exhaust pipes removed, start the engine and load the engine on a dynamometer to see if the problem is corrected.
17. Defective Turbocharger:
Check inlet manifold for oil and repair turbocharger.
Blue Smoke
Probable Cause(s):
18. Oil level in engine too high:
Do not put too much oil in the crankcase. If the oil level in the crankcase goes up as the engine is used, check for fuel in the lubrication oil. Refer to Problem 29: Fuel In Lubrication Oil.
19. Failure of turbocharger oil seal:
Check inlet manifold for oil and repair turbocharger.
20. Worn or broken valve guides:
See the Specifications Section of the Service Manual for the maximum permissible wear of the valve guides. If necessary, recondition the cylinder head.
21. Worn piston rings and/or cylinder walls:
Worn piston rings and/or cylinder walls can be the cause of blue smoke and can cause a loss of compression. This condition can cause more than the normal amount of fumes (blow-by) coming from the crankcase breather. The 8T2700 Indicator Group is used to check the amount of blow-by. The test procedure is in Special Instruction, SEHS8712. If necessary make a visual inspection of the cylinder walls and piston rings. Measure the cylinder walls and piston rings. For the cylinder and piston ring specifications see the Specification Section of the Service Manual. Repair and replace parts as necessary.
NOTE: High wear at low hours is normally caused by dirt coming into the engine with the inlet air.
22. Wear or damage to pistons:
Check piston ring to groove clearance. Pistons which have worn grooves and pistons with damage or defects can cause blue smoke and too much oil consumption. Make sure the oil return holes under the oil ring are open. Replace pistons as necessary.