Author Topic: Smoke color summary  (Read 8971 times)

September 26, 2007, 11:36:50 pm


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Smoke color summary
« on: September 26, 2007, 11:36:50 pm »
A summary of your diesel smoke colors

The first category is blue-white smoke:

Blue-white smoke may be noticed at engine start-up whether the engine is at normal operating temperature or not. Blue-white smoke can be observed at all ambient temperatures and should not last longer than a minute or two after the vehicle has been driven. Blue-white smoke can return when ambient temperature is below 10 degrees C (50 degrees F), and  after the engine is   warmed up due to extended idling. This is due to combustion chambers cooling own during periods of extended idling time. Heavy blue-white smoke may also occur if the engine is operated at full throttle with the transmission in neutral or park. If you see continuous Blue-white smoke while driving, then you probably have air being sucked into the fuel system.

The second category is white smoke:

White smoke and blue-white smoke share some of the same characteristics. White smoke is fuel not being burned. Extreme white smoke can be caused by the combustion chambers cooling down. One cause of this could be incorrect injection pump timing. Coolant getting into the combustion chamber can cause white smoke also. Possible causes are blown head gaskets, cracked heads cavitation, etc.

The third category is black smoke:

Black smoke is caused by an over rich mixture and normally occurs whenever the engine is working hard. Like going up a steep grade, being loaded heavy or during heavy acceleration. More black smoke can be observed when the vehicle is operated at higher altitudes because the air is thinner. A dirty air filter is also another cause of excessive black smoke. If black smoke is noticed while the engine is idling at low altitude or under normal driving conditions this condition should be diagnosed a.s.a.p. to prevent engine damage.

The fourth category is blue smoke:

Blue smoke is not normal and you do not want to be driving behind a truck that produces it. Blue smoke occurs when oil is entering the combustion chamber and is burning along with the fuel. Blue smoke usual indicates a condition which should be corrected a.s.a.p. Blue smoke also smells like oil burning. Possible causes include valve seals or cracked piston rings.