407914-2050 ZEXEL CONTROL UNIT Cross 4079142050

White Smoke
Possible Causes/Corrections
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. 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. Engine Operating Temperature Too Low/This can cause white smoke on start-up. If the smoke is slow to clear from the exhaust, check and make a replacement of the thermostat if needed. Low Quality Fuel/Test the engine using fuel according to recommendations by Caterpillar Tractor Co. For more information see Special Instruction, Form No. SEHS7067, Fuel Recommendations For Caterpillar Diesel Engines. 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. If the engine will not start, loosen a fuel injection line nut and crank the engine until fuel comes out. Tighten the fuel line nut. Start the engine. If the engine still does not run smooth or releases a large amount of white smoke, loosen the fuel line nuts one at a time until the fuel that comes out is free of air. Tighten the fuel line nuts. If the air can not be removed in this way, put 35 kPa (5 psi) of air pressure to the fuel tank.
Do not use more than 55 kPa (8 psi) of air pressure in the fuel tank or damage to the tank may result.
Check for leakage at the connections between the fuel tank and the fuel transfer pump. If leaks are found, tighten the connections or replace the lines. If there are no visual leaks, remove the fuel supply line from the tank and connect it to an outside fuel supply. If this corrects the problem, the suction line (standpipe) inside the fuel tank has a leak. Fuel Injection Timing Not Correct/Check and make necessary adjustments as in Testing and Adjusting section of this Service Manual. Valve Adjustment Not Correct/Check and make necessary adjustments as in Testing and Adjusting section of this Service Manual. Intake valve clearance is 0.38 mm (.015 in.) and exhaust valve clearance is 0.64 mm (.025 in.). Bad Fuel Nozzle(s)/Bad fuel nozzles will normally cause the engine to "misfire" and run rough, but can cause too much smoke with the engine still running smooth. Remove the fuel nozzles and test as in Testing and Adjusting section of this Service Manual. Misfiring Cylinder(s)/See MISFIRING AND RUNNING ROUGH. Coolant Leakage Into Combustion Chamber/Coolant in the combustion chamber can