3116 and 3126 Truck Engines Problem Too Much Exhaust Smoke (Black Or Gray)

Engine Runs Smoothly (Go to Step 1)

Probable Cause(s):

* Not Enough Air For Combustion
* Exhaust System Restriction
* Low Quality Fuel
* Valve Adjustment Is Not Correct Or Valve Leakage
* Defective Unit Injector
* Low Injection Actuation Pressure
* Defect In Boost Sensor

Engine Runs Rough (Go to Step 9)

* Misfiring Cylinders
* Air In Fuel System

1. Not enough air for combustion:

A. Restriction in air cleaner:

If the air cleaner has a restriction indicator, see if the red piston is in view. If there is no restriction indicator, restriction can be checked with a water manometer or a vacuum gauge (which measures in inches of water). Make a connection of the piping between the air cleaner and the air inlet of the turbocharger. Check with the engine running at full load rpm. Maximum restriction is 6.22 kPa (25 inches of water). If a guage is not available, visually check the air cleaner element for dirt. If the element is dirty, clean the element or install a new element.
B. Air inlet piping damage or restriction:

Make a visual inspection of the air inlet system and check for damage to piping, rags in the inlet piping, or damage to the rain cap or the cap is pushed too far onto the inlet pipe. If no damage is seen, check the inlet restriction with a clean air cleaner element.
C. Turbocharger not operating properly:

Check turbocharger for proper operation.

2. 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 10.0 kPa (40 inches of water). If a guage 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.
3. Low quality fuel:

Test the engine with fuel according to recommendations by Caterpillar Inc.
4. Valve adjustment is not correct or valve leakage:

Check and make necessary adjustments as per Testing and Adjusting Section of the Service Manual.
5. Defective unit injectors:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Injector Solenoid Circuit Test.
6. Low injection actuation pressure:

If the injection actuation pressure is less than desired, then the unit injectors may not be able to inject fuel. The injection Actuation Pressure Control Valve could cause this if debris is clogging the valve. Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Injection Actuation Pressure Test.
7. Defect in boost sensor:

Using an electronic service tool check for logged or active diagnostic codes. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting, SENR6566, for Excessive Black Smoke.

Engine Runs Rough

Probable Cause(s):
9. Misfiring cylinders:

Refer to Problem 4: Engine Misfiring Or Running Rough.
10. 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.