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 TM 55-1905-223-24-3
2-20. White Smoke-General Information . White smoke is the result of incomplete combustion and is
generally associated with engine startup at low ambient temperatures. This condition is more predominant on
high horsepower fixed injection timing engines because the fuel and combustion systems are optimized for
maximum performance and for reliability and durability under high load operating conditions.
a. Starting at Low Ambient Temperatures. These engines can have two or three cylinders that misfire or
have incomplete combustion when the engine is started at low ambient temperatures. The fuel that is injected
into the cylinders that are misfiring is exhausted into the atmosphere as unburned hydrocarbons which cool,
condense, and appear as white smoke. As the cylinder temperature and subsequently the coolant temperature
rise, the misfiring cylinders begin to sustain combustion which decreases the hydrocarbon level in the exhaust,
resulting in less white smoke being produced.
b. Level of White Smoke. Since white smoke is a normal characteristic of high horsepower, heavy-duty
diesel engines during startup at low ambient temperatures, it is extremely important to determine if the level of
white smoke is significantly higher than normal for a particular engine model before making any attempt to
correct a complaint. This can be accomplished by comparing the level of white smoke from one unit to another
which has the same chasses configuration and engine model. If a significant difference in the level of white
smoke between the two units is noted under the same operating conditions, refer to Table 2-2, Item 33,
"Excessive White Smoke in Idle," for corrective action.
2-21. Generator Troubleshooting-General Information . Troubleshooting generators can start with finding
out as much of the past history of the unit as possible. Record the generator model number, part number,
serial number, voltage and Kw ratings. Were there any past failures and how many hours are on the unit?
Question the operator about the types of loads encountered and ask what was observed when the failure was
detected. Were there any peculiar noises or odors? Use a systematic approach to isolate the problem.
2-22. Troubleshooting Index and Table . Both a symptom index and a troubleshooting table are provided.
The symptom index will help you locate the information you need for troubleshooting.
2-21
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